diff --git a/components/multithreadprocs/examples/testmtp1.lpi b/components/multithreadprocs/examples/testmtp1.lpi
new file mode 100644
index 000000000..094fa653b
--- /dev/null
+++ b/components/multithreadprocs/examples/testmtp1.lpi
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<CONFIG>
+  <ProjectOptions>
+    <PathDelim Value="/"/>
+    <Version Value="6"/>
+    <General>
+      <SessionStorage Value="InProjectDir"/>
+      <MainUnit Value="0"/>
+      <TargetFileExt Value=""/>
+    </General>
+    <VersionInfo>
+      <ProjectVersion Value=""/>
+    </VersionInfo>
+    <PublishOptions>
+      <Version Value="2"/>
+      <IgnoreBinaries Value="False"/>
+      <IncludeFileFilter Value="*.(pas|pp|inc|lfm|lpr|lrs|lpi|lpk|sh|xml)"/>
+      <ExcludeFileFilter Value="*.(bak|ppu|ppw|o|so);*~;backup"/>
+    </PublishOptions>
+    <RunParams>
+      <local>
+        <FormatVersion Value="1"/>
+        <LaunchingApplication PathPlusParams="/usr/X11R6/bin/xterm -T 'Lazarus Run Output' -e $(LazarusDir)/tools/runwait.sh $(TargetCmdLine)"/>
+      </local>
+    </RunParams>
+    <RequiredPackages Count="1">
+      <Item1>
+        <PackageName Value="MultiThreadProcsLaz"/>
+        <MinVersion Valid="True"/>
+        <DefaultFilename Value="../multithreadprocslaz.lpk"/>
+      </Item1>
+    </RequiredPackages>
+    <Units Count="1">
+      <Unit0>
+        <Filename Value="testmtp1.lpr"/>
+        <IsPartOfProject Value="True"/>
+      </Unit0>
+    </Units>
+  </ProjectOptions>
+  <CompilerOptions>
+    <Version Value="8"/>
+    <Other>
+      <CompilerPath Value="$(CompPath)"/>
+    </Other>
+  </CompilerOptions>
+</CONFIG>
diff --git a/components/multithreadprocs/examples/testmtp1.lpr b/components/multithreadprocs/examples/testmtp1.lpr
new file mode 100644
index 000000000..d2762df63
--- /dev/null
+++ b/components/multithreadprocs/examples/testmtp1.lpr
@@ -0,0 +1,367 @@
+program TestMTP1;
+
+{$mode objfpc}{$H+}
+
+uses
+  {$IFDEF UNIX}
+  cthreads, cmem,
+  {$ENDIF}
+  Math, SysUtils, Classes, MTProcs, MTPUtils, MultiThreadProcsLaz;
+
+type
+
+  { TTestItem }
+
+  TTestItem = class
+  private
+    FIndex: int64;
+  public
+    property Index: int64 read FIndex;
+    constructor Create(NewIndex: int64);
+  end;
+
+  { TTests }
+
+  TTests = class
+  public
+    procedure Work(Seconds: integer);
+
+    // RTLeventSetEvent, RTLeventWaitFor
+    procedure TestRTLevent_Set_WaitFor;
+
+    // single thread test
+    procedure TestSingleThread;
+    procedure MTPLoop_TestSingleThread(Index: PtrInt; Data: Pointer;
+                                       Item: TMultiThreadProcItem);
+
+    // two threads test: run once
+    procedure TestTwoThreads1;
+    procedure MTPLoop_TestTwoThreads1(Index: PtrInt; Data: Pointer;
+                                      Item: TMultiThreadProcItem);
+
+    // 0 runs two seconds,
+    // 1 runs a second then waits for 0 then runs a second
+    // 2 runs a second then waits for 1
+    // 3 waits for 0
+    // 4 waits for 1
+    // 5 waits for 2
+    procedure TestMTPWaitForIndex;
+    procedure MTPLoop_TestMTPWaitForIndex(Index: PtrInt; Data: Pointer;
+                                          Item: TMultiThreadProcItem);
+
+    // two threads test: various run times
+    procedure TestMTPTwoThreads2;
+    procedure MTPLoop_TestTwoThreads2(Index: PtrInt; Data: Pointer;
+                                      Item: TMultiThreadProcItem);
+
+    // test exception in starter thread
+    procedure TestMTPExceptionInStarterThread;
+    procedure MTPLoop_TestExceptionInStarterThread(Index: PtrInt; Data: Pointer;
+                                                   Item: TMultiThreadProcItem);
+
+    // test exception in helper thread
+    procedure TestMTPExceptionInHelperThread;
+    procedure MTPLoop_TestExceptionInHelperThread(Index: PtrInt; Data: Pointer;
+                                                  Item: TMultiThreadProcItem);
+
+    // test parallel sort
+    procedure TestMTPSort;
+    procedure MTPLoop_TestDoubleMTPSort(Index: PtrInt; Data: Pointer;
+                                        Item: TMultiThreadProcItem);
+  end;
+
+{ TTestItem }
+
+constructor TTestItem.Create(NewIndex: int64);
+begin
+  FIndex:=NewIndex;
+end;
+
+{ TTests }
+
+procedure TTests.Work(Seconds: integer);
+var
+  Start: TDateTime;
+begin
+  Start:=Now;
+  while (Now-Start)*86400<Seconds do if GetCurrentDir='' then ;
+end;
+
+procedure TTests.TestRTLevent_Set_WaitFor;
+var
+  e: PRTLEvent;
+begin
+  e:=RTLEventCreate;
+  RTLeventSetEvent(e);
+  RTLeventWaitFor(e);
+  RTLeventdestroy(e);
+end;
+
+procedure TTests.TestSingleThread;
+begin
+  ProcThreadPool.DoParallel(@MTPLoop_TestSingleThread,1,3,nil,1);
+end;
+
+procedure TTests.MTPLoop_TestSingleThread(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+begin
+  writeln('TTests.MTPLoop_TestSingleThread Index=',Index);
+end;
+
+procedure TTests.TestTwoThreads1;
+begin
+  WriteLn('TTests.TestTwoThreads1 START');
+  ProcThreadPool.DoParallel(@MTPLoop_TestTwoThreads1,1,2,nil,2);
+  WriteLn('TTests.TestTwoThreads1 END');
+end;
+
+procedure TTests.MTPLoop_TestTwoThreads1(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+var
+  i: Integer;
+begin
+  for i:=1 to 3 do begin
+    WriteLn('TTests.MTPLoop_TestTwoThreads1 Index=',Index,' ',i);
+    Work(1);
+  end;
+end;
+
+procedure TTests.TestMTPWaitForIndex;
+var
+  IndexStates: PInteger;
+begin
+  ProcThreadPool.MaxThreadCount:=8;
+  IndexStates:=nil;
+  GetMem(IndexStates,SizeOf(Integer)*10);
+  FillByte(IndexStates^,SizeOf(Integer)*10,0);
+  WriteLn('TTests.TestMTPWaitForIndex START');
+  ProcThreadPool.DoParallel(@MTPLoop_TestMTPWaitForIndex,0,5,IndexStates);
+  FreeMem(IndexStates);
+  WriteLn('TTests.TestMTPWaitForIndex END');
+end;
+
+procedure TTests.MTPLoop_TestMTPWaitForIndex(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+    // 0 runs two seconds,
+    // 1 runs a second then waits for 0 then runs a second
+    // 2 runs a second then waits for 1
+    // 3 waits for 0
+    // 4 waits for 1
+    // 5 waits for 2
+
+  procedure WaitFor(OtherIndex: PtrInt);
+  begin
+    WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' waiting for '+IntToStr(OtherIndex)+' ...');
+    Item.WaitForIndex(OtherIndex);
+    WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' waited for '+IntToStr(OtherIndex)+'. working ...');
+    if PInteger(Data)[OtherIndex]<>2 then begin
+      WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' ERROR: waited for '+IntToStr(OtherIndex)+' failed: OtherState='+IntToStr(PInteger(Data)[OtherIndex]));
+    end;
+  end;
+
+begin
+  WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' START');
+  if PInteger(Data)[Index]<>0 then begin
+    WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' ERROR: IndexState='+IntToStr(PInteger(Data)[Index]));
+  end;
+  PInteger(Data)[Index]:=1;
+  case Index of
+  0: Work(2);
+  1:begin
+      Work(1);
+      WaitFor(0);
+      Work(1);
+    end;
+  2:begin
+      Work(1);
+      WaitFor(1);
+    end;
+  3:begin
+      WaitFor(0);
+    end;
+  4:begin
+      WaitFor(1);
+    end;
+  5:begin
+      WaitFor(2);
+    end;
+  end;
+  WriteLn('TTests.MTPLoop_TestMTPWaitForIndex Index='+IntToStr(Index)+' END');
+  PInteger(Data)[Index]:=2;
+end;
+
+procedure TTests.TestMTPTwoThreads2;
+begin
+  WriteLn('TTests.TestMTPTwoThreads1 START');
+  ProcThreadPool.DoParallel(@MTPLoop_TestTwoThreads2,1,6,nil,2);
+  WriteLn('TTests.TestMTPTwoThreads1 END');
+end;
+
+procedure TTests.MTPLoop_TestTwoThreads2(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+var
+  i: Integer;
+begin
+  for i:=1 to (Index mod 3)+1 do begin
+    WriteLn('TTests.MTPLoop_TestTwoThreads1 Index=',Index,' i=',i,' ID=',PtrUint(GetThreadID));
+    Work(1);
+  end;
+end;
+
+type
+  TMyException = class(Exception);
+
+procedure TTests.TestMTPExceptionInStarterThread;
+var
+  IndexStates: PInteger;
+begin
+  WriteLn('TTests.TestMTPExceptionInStarterThread START');
+  ProcThreadPool.MaxThreadCount:=8;
+  IndexStates:=nil;
+  GetMem(IndexStates,SizeOf(Integer)*10);
+  FillByte(IndexStates^,SizeOf(Integer)*10,0);
+  try
+    ProcThreadPool.DoParallel(@MTPLoop_TestExceptionInStarterThread,1,3,IndexStates,2);
+  except
+    on E: Exception do begin
+      WriteLn('TTests.TestMTPExceptionInHelperThread E.ClassName=',E.ClassName,' E.Message=',E.Message);
+    end;
+  end;
+  FreeMem(IndexStates);
+  WriteLn('TTests.TestMTPExceptionInStarterThread END');
+end;
+
+procedure TTests.MTPLoop_TestExceptionInStarterThread(Index: PtrInt;
+  Data: Pointer; Item: TMultiThreadProcItem);
+begin
+  WriteLn('TTests.MTPLoop_TestExceptionInStarterThread START Index='+IntToStr(Index));
+  if PInteger(Data)[Index]<>0 then
+    WriteLn('TTests.MTPLoop_TestExceptionInStarterThread Index='+IntToStr(Index)+' ERROR: IndexState='+IntToStr(PInteger(Data)[Index]));
+  PInteger(Data)[Index]:=1;
+  case Index of
+  1:
+    begin
+      // Main Thread
+      Work(1);
+      WriteLn('TTests.MTPLoop_TestExceptionInStarterThread raising exception in Index='+IntToStr(Index)+' ...');
+      raise Exception.Create('Exception in starter thread');
+    end;
+  else
+    Work(Index);
+  end;
+  PInteger(Data)[Index]:=2;
+  WriteLn('TTests.MTPLoop_TestExceptionInStarterThread END Index='+IntToStr(Index));
+end;
+
+procedure TTests.TestMTPExceptionInHelperThread;
+var
+  IndexStates: PInteger;
+begin
+  WriteLn('TTests.TestMTPExceptionInHelperThread START');
+  ProcThreadPool.MaxThreadCount:=8;
+  IndexStates:=nil;
+  GetMem(IndexStates,SizeOf(Integer)*10);
+  FillByte(IndexStates^,SizeOf(Integer)*10,0);
+  try
+    ProcThreadPool.DoParallel(@MTPLoop_TestExceptionInHelperThread,1,3,IndexStates,2);
+  except
+    on E: Exception do begin
+      WriteLn('TTests.TestMTPExceptionInHelperThread E.ClassName=',E.ClassName,' E.Message=',E.Message);
+    end;
+  end;
+  FreeMem(IndexStates);
+  WriteLn('TTests.TestMTPExceptionInHelperThread END');
+end;
+
+procedure TTests.MTPLoop_TestExceptionInHelperThread(Index: PtrInt;
+  Data: Pointer; Item: TMultiThreadProcItem);
+begin
+  WriteLn('TTests.MTPLoop_TestExceptionInHelperThread START Index='+IntToStr(Index));
+  if PInteger(Data)[Index]<>0 then
+    WriteLn('TTests.MTPLoop_TestExceptionInHelperThread Index='+IntToStr(Index)+' ERROR: IndexState='+IntToStr(PInteger(Data)[Index]));
+  PInteger(Data)[Index]:=1;
+  case Index of
+  2:
+    begin
+      // Helper Thread 2
+      Work(1);
+      WriteLn('TTests.MTPLoop_TestExceptionInHelperThread raising exception in Index='+IntToStr(Index)+' ...');
+      raise TMyException.Create('Exception in helper thread');
+    end;
+  else
+    Work(Index+1);
+  end;
+  PInteger(Data)[Index]:=2;
+  WriteLn('TTests.MTPLoop_TestExceptionInHelperThread END Index='+IntToStr(Index));
+end;
+
+function CompareTestItems(Data1, Data2: Pointer): integer;
+begin
+  if TTestItem(Data1).Index>TTestItem(Data2).Index then
+    Result:=1
+  else if TTestItem(Data1).Index<TTestItem(Data2).Index then
+    Result:=-1
+  else
+    Result:=0;
+end;
+
+procedure TTests.TestMTPSort;
+var
+  OuterLoop: Integer;
+  InnerLoop: Integer;
+begin
+  OuterLoop:=1;
+  InnerLoop:=0;
+  if Paramcount=1 then begin
+    InnerLoop:=StrToInt(ParamStr(1));
+  end else if Paramcount=2 then begin
+    OuterLoop:=StrToInt(ParamStr(1));
+    InnerLoop:=StrToInt(ParamStr(2));
+  end;
+  writeln('TTests.TestMTPSort Running ',OuterLoop,'x',InnerLoop);
+  ProcThreadPool.DoParallel(@MTPLoop_TestDoubleMTPSort,1,OuterLoop,@InnerLoop);
+end;
+
+procedure TTests.MTPLoop_TestDoubleMTPSort(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+var
+  i: Integer;
+  List: TFPList;
+  t: double;
+begin
+  // create an unsorted list of values
+  List:=TFPList.Create;
+  for i:=1 to 10000000 do List.Add(TTestItem.Create(Random(99999999999)));
+  //QuickSort(List,0,List.Count-1,@AnsiCompareText);
+
+  t:=Now;
+  ParallelSortFPList(List,@CompareTestItems,PInteger(Data)^);
+  t:=Now-t;
+  writeln('TTests.TestMTPSort ',t*86400);
+  // check
+  sleep(1);
+  for i:=0 to List.Count-2 do
+    if CompareTestItems(List[i],List[i+1])>0 then raise Exception.Create('not sorted');
+
+  for i:=0 to List.Count-1 do
+    TObject(List[i]).Free;
+  List.Free;
+end;
+
+var
+  Tests: TTests;
+begin
+  writeln('threads=',ProcThreadPool.MaxThreadCount);
+  ProcThreadPool.MaxThreadCount:=8;
+  Tests:=TTests.Create;
+  //Tests.Test1;
+  //Tests.Test2;
+  //Tests.TestTwoThreads2;
+  //Tests.TestRTLevent_Set_WaitFor;
+  //Tests.TestMTPWaitForIndex;
+  //Tests.TestMTPExceptionInStarterThread;
+  Tests.TestMTPExceptionInHelperThread;
+  //Tests.TestMTPSort;
+  Tests.Free;
+end.
+
diff --git a/components/multithreadprocs/mtpcpu.pas b/components/multithreadprocs/mtpcpu.pas
new file mode 100644
index 000000000..93e864e28
--- /dev/null
+++ b/components/multithreadprocs/mtpcpu.pas
@@ -0,0 +1,90 @@
+{ System depending code for light weight threads.
+
+  This file is part of the Free Pascal run time library.
+
+  Copyright (C) 2008 Mattias Gaertner mattias@freepascal.org
+
+  See the file COPYING.FPC, included in this distribution,
+  for details about the copyright.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+unit MTPCPU;
+
+{$mode objfpc}{$H+}
+
+interface
+
+{$IF defined(windows)}
+uses Windows;
+{$ELSEIF defined(freebsd) or defined(darwin)}
+uses ctypes, sysctl;
+{$ELSEIF defined(linux)}
+{$linklib c}
+uses ctypes;
+{$ENDIF}
+
+function GetSystemThreadCount: integer;
+
+implementation
+
+{$IFDEF Linux}
+const _SC_NPROCESSORS_ONLN = 83;
+function sysconf(i: cint): clong; cdecl; external name 'sysconf';
+{$ENDIF}
+
+function GetSystemThreadCount: integer;
+// returns a good default for the number of threads on this system
+{$IF defined(windows)}
+//returns total number of processors available to system including logical hyperthreaded processors
+var
+  i: Integer;
+  ProcessAffinityMask, SystemAffinityMask: DWORD;
+  Mask: DWORD;
+  SystemInfo: SYSTEM_INFO;
+begin
+  if GetProcessAffinityMask(GetCurrentProcess, ProcessAffinityMask, SystemAffinityMask)
+  then begin
+    Result := 0;
+    for i := 0 to 31 do begin
+      Mask := 1 shl i;
+      if (ProcessAffinityMask and Mask)<>0 then
+        inc(Result);
+    end;
+  end else begin
+    //can't get the affinity mask so we just report the total number of processors
+    GetSystemInfo(SystemInfo);
+    Result := SystemInfo.dwNumberOfProcessors;
+  end;
+end;
+{$ELSEIF defined(UNTESTEDsolaris)}
+  begin
+    t = sysconf(_SC_NPROC_ONLN);
+  end;
+{$ELSEIF defined(freebsd) or defined(darwin)}
+var
+  mib: array[0..1] of cint;
+  len: cint;
+  t: cint;
+begin
+  mib[0] := CTL_HW;
+  mib[1] := HW_NCPU;
+  len := sizeof(t);
+  fpsysctl(pchar(@mib), 2, @t, @len, Nil, 0);
+  Result:=t;
+end;
+{$ELSEIF defined(linux)}
+  begin
+    Result:=sysconf(_SC_NPROCESSORS_ONLN);
+  end;
+{$ELSE}
+  begin
+    Result:=1;
+  end;
+{$ENDIF}
+
+end.
+
diff --git a/components/multithreadprocs/mtprocs.pas b/components/multithreadprocs/mtprocs.pas
new file mode 100644
index 000000000..97bed85b0
--- /dev/null
+++ b/components/multithreadprocs/mtprocs.pas
@@ -0,0 +1,796 @@
+{ Unit for light weight threads.
+
+  This file is part of the Free Pascal run time library.
+
+  Copyright (C) 2008 Mattias Gaertner mattias@freepascal.org
+
+  See the file COPYING.FPC, included in this distribution,
+  for details about the copyright.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+{
+  Abstract:
+    Light weight threads.
+    This unit provides methods to easily run a procedure/method with several
+    threads at once.
+}
+unit MTProcs;
+
+{$mode objfpc}{$H+}
+
+{$inline on}
+
+interface
+
+uses
+  Classes, SysUtils, MTPCPU;
+
+type
+  TProcThreadGroup = class;
+  TProcThreadPool = class;
+
+  { TMultiThreadProcItem }
+
+  TMTPThreadState = (
+    mtptsNone,
+    mtptsActive,
+    mtptsWaitingForIndex,
+    mtptsWaitingFailed,
+    mtptsInactive,
+    mtptsTerminated
+    );
+
+  TMultiThreadProcItem = class
+  private
+    FGroup: TProcThreadGroup;
+    FIndex: PtrInt;
+    FWaitingForIndexEnd: PtrInt;
+    FWaitingForIndexStart: PtrInt;
+    fWaitForPool: PRTLEvent;
+    FState: TMTPThreadState;
+  public
+    destructor Destroy; override;
+    function WaitForIndexRange(StartIndex, EndIndex: PtrInt): boolean;
+    function WaitForIndex(Index: PtrInt): boolean; inline;
+    property Index: PtrInt read FIndex;
+    property Group: TProcThreadGroup read FGroup;
+    property WaitingForIndexStart: PtrInt read FWaitingForIndexStart;
+    property WaitingForIndexEnd: PtrInt read FWaitingForIndexEnd;
+  end;
+
+  { TProcThread }
+
+  TMTPThreadList = (
+    mtptlPool,
+    mtptlGroup
+    );
+
+  TProcThread = class(TThread)
+  private
+    FItem: TMultiThreadProcItem;
+    FNext, FPrev: array[TMTPThreadList] of TProcThread;
+    procedure AddToList(var First: TProcThread; ListType: TMTPThreadList); inline;
+    procedure RemoveFromList(var First: TProcThread; ListType: TMTPThreadList); inline;
+    procedure Terminating(aPool: TProcThreadPool; E: Exception);
+  public
+    constructor Create;
+    destructor Destroy; override;
+    procedure Execute; override;
+    property Item: TMultiThreadProcItem read FItem;
+  end;
+
+  TMTMethod = procedure(Index: PtrInt; Data: Pointer;
+                        Item: TMultiThreadProcItem) of object;
+  TMTProcedure = procedure(Index: PtrInt; Data: Pointer;
+                           Item: TMultiThreadProcItem);
+
+  { TProcThreadGroup
+    Each task creates a new group of threads.
+    A group can either need more threads or it has finished and waits for its
+    threads to end.
+    The thread that created the group is not in the list FFirstThread. }
+
+  TMTPGroupState = (
+    mtpgsNone,
+    mtpgsNeedThreads, // the groups waiting for more threads to help
+    mtpgsFinishing,   // the groups waiting for its threads to finish
+    mtpgsException    // there was an exception => close asap
+    );
+
+  TProcThreadGroup = class
+  private
+    FEndIndex: PtrInt;
+    FFirstRunningIndex: PtrInt;
+    FLastRunningIndex: PtrInt;
+    FStarterItem: TMultiThreadProcItem;
+    FMaxThreads: PtrInt;
+    FPool: TProcThreadPool;
+    FStartIndex: PtrInt;
+    FTaskData: Pointer;
+    FNext, FPrev: TProcThreadGroup;
+    FState: TMTPGroupState;
+    FTaskMethod: TMTMethod;
+    FFirstThread: TProcThread;
+    FTaskProcdure: TMTProcedure;
+    FThreadCount: PtrInt;
+    FException: Exception;
+    procedure AddToList(var First: TProcThreadGroup; ListType: TMTPGroupState); inline;
+    procedure RemoveFromList(var First: TProcThreadGroup); inline;
+    function NeedMoreThreads: boolean; inline;
+    procedure AddThread(AThread: TProcThread);
+    procedure RemoveThread(AThread: TProcThread); inline;
+    procedure Run(Index: PtrInt; Data: Pointer; Item: TMultiThreadProcItem); inline;
+    procedure IndexComplete(Index: PtrInt);
+    procedure WakeThreadsWaitingForIndex;
+    function HasFinishedIndex(aStartIndex, aEndIndex: PtrInt): boolean;
+    procedure EnterExceptionState(E: Exception);
+  public
+    constructor Create;
+    destructor Destroy; override;
+    property Pool: TProcThreadPool read FPool;
+    property StartIndex: PtrInt read FStartIndex;
+    property EndIndex: PtrInt read FEndIndex;
+    property FirstRunningIndex: PtrInt read FFirstRunningIndex; // first started
+    property LastRunningIndex: PtrInt read FLastRunningIndex; // last started
+    property TaskData: Pointer read FTaskData;
+    property TaskMethod: TMTMethod read FTaskMethod;
+    property TaskProcdure: TMTProcedure read FTaskProcdure;
+    property MaxThreads: PtrInt read FMaxThreads;
+    property StarterItem: TMultiThreadProcItem read FStarterItem;
+  end;
+
+  { TLightWeightThreadPool
+    Group 0 are the inactive threads }
+
+  TProcThreadPool = class
+  private
+    FMaxThreadCount: PtrInt;
+    FThreadCount: PtrInt;
+    FFirstInactiveThread: TProcThread;
+    FFirstActiveThread: TProcThread;
+    FFirstTerminatedThread: TProcThread;
+    FFirstGroupNeedThreads: TProcThreadGroup;
+    FFirstGroupFinishing: TProcThreadGroup;
+    FCritSection: TRTLCriticalSection;
+    FDestroying: boolean;
+    procedure SetMaxThreadCount(const AValue: PtrInt);
+    procedure CleanTerminatedThreads;
+    procedure DoParallelIntern(const AMethod: TMTMethod;
+      const AProc: TMTProcedure;
+      StartIndex, EndIndex: PtrInt;
+      Data: Pointer = nil; MaxThreads: PtrInt = 0);
+  public
+    constructor Create;
+    destructor Destroy; override;
+    procedure EnterPoolCriticalSection; inline;
+    procedure LeavePoolCriticalSection; inline;
+
+    procedure DoParallel(const AMethod: TMTMethod;
+      StartIndex, EndIndex: PtrInt;
+      Data: Pointer = nil; MaxThreads: PtrInt = 0); inline;
+    procedure DoParallel(const AProc: TMTProcedure;
+      StartIndex, EndIndex: PtrInt;
+      Data: Pointer = nil; MaxThreads: PtrInt = 0); inline;
+  public
+    property MaxThreadCount: PtrInt read FMaxThreadCount write SetMaxThreadCount;
+    property ThreadCount: PtrInt read FThreadCount;
+  end;
+
+var
+  ProcThreadPool: TProcThreadPool = nil;
+
+implementation
+
+{ TMultiThreadProcItem }
+
+destructor TMultiThreadProcItem.Destroy;
+begin
+  if fWaitForPool<>nil then begin
+    RTLeventdestroy(fWaitForPool);
+    fWaitForPool:=nil;
+  end;
+  inherited Destroy;
+end;
+
+function TMultiThreadProcItem.WaitForIndexRange(
+  StartIndex, EndIndex: PtrInt): boolean;
+var
+  aPool: TProcThreadPool;
+begin
+  //WriteLn('TLightWeightThreadItem.WaitForIndexRange START Index='+IntToStr(Index)+' StartIndex='+IntToStr(StartIndex)+' EndIndex='+IntToStr(EndIndex));
+  if (EndIndex>=Index) then exit(false);
+  if EndIndex<StartIndex then exit(true);
+  if Group=nil then exit(true); // a single threaded group has no group object
+  // multi threaded group
+  aPool:=Group.Pool;
+  if aPool.FDestroying then exit(false); // no more wait allowed
+  aPool.EnterPoolCriticalSection;
+  try
+    if Group.FState=mtpgsException then begin
+      //WriteLn('TLightWeightThreadItem.WaitForIndexRange Index='+IntToStr(Index)+', Group closing because of error');
+      exit(false);
+    end;
+    if Group.HasFinishedIndex(StartIndex,EndIndex) then begin
+      //WriteLn('TLightWeightThreadItem.WaitForIndexRange Index='+IntToStr(Index)+', range already finished');
+      exit(true);
+    end;
+    FState:=mtptsWaitingForIndex;
+    FWaitingForIndexStart:=StartIndex;
+    FWaitingForIndexEnd:=EndIndex;
+    if fWaitForPool=nil then
+      fWaitForPool:=RTLEventCreate;
+    RTLeventResetEvent(fWaitForPool);
+  finally
+    aPool.LeavePoolCriticalSection;
+  end;
+  //WriteLn('TLightWeightThreadItem.WaitForIndexRange '+IntToStr(Index)+' waiting ... ');
+  RTLeventWaitFor(fWaitForPool);
+  Result:=FState=mtptsActive;
+  FState:=mtptsActive;
+  //WriteLn('TLightWeightThreadItem.WaitForIndexRange END '+IntToStr(Index));
+end;
+
+function TMultiThreadProcItem.WaitForIndex(Index: PtrInt): boolean; inline;
+begin
+  Result:=WaitForIndexRange(Index,Index);
+end;
+
+{ TProcThread }
+
+procedure TProcThread.AddToList(var First: TProcThread;
+  ListType: TMTPThreadList);
+begin
+  FNext[ListType]:=First;
+  if FNext[ListType]<>nil then
+    FNext[ListType].FPrev[ListType]:=Self;
+  First:=Self;
+end;
+
+procedure TProcThread.RemoveFromList(var First: TProcThread;
+  ListType: TMTPThreadList);
+begin
+  if First=Self then
+    First:=FNext[ListType];
+  if FNext[ListType]<>nil then
+    FNext[ListType].FPrev[ListType]:=FPrev[ListType];
+  if FPrev[ListType]<>nil then
+    FPrev[ListType].FNext[ListType]:=FNext[ListType];
+  FNext[ListType]:=nil;
+  FPrev[ListType]:=nil;
+end;
+
+procedure TProcThread.Terminating(aPool: TProcThreadPool;
+  E: Exception);
+begin
+  aPool.EnterPoolCriticalSection;
+  try
+    // remove from group
+    if Item.FGroup<>nil then begin
+      // an exception occured
+      Item.FGroup.EnterExceptionState(E);
+      Item.FGroup.RemoveThread(Self);
+      Item.FGroup:=nil;
+    end;
+    // move to pool's terminated threads
+    case Item.FState of
+    mtptsActive:   RemoveFromList(aPool.FFirstActiveThread,mtptlPool);
+    mtptsInactive: RemoveFromList(aPool.FFirstInactiveThread,mtptlPool);
+    end;
+    AddToList(aPool.FFirstTerminatedThread,mtptlPool);
+    Item.FState:=mtptsTerminated;
+  finally
+    aPool.LeavePoolCriticalSection;
+  end;
+end;
+
+constructor TProcThread.Create;
+begin
+  inherited Create(true);
+  fItem:=TMultiThreadProcItem.Create;
+  fItem.fWaitForPool:=RTLEventCreate;
+end;
+
+destructor TProcThread.Destroy;
+begin
+  FreeAndNil(FItem);
+  inherited Destroy;
+end;
+
+procedure TProcThread.Execute;
+var
+  aPool: TProcThreadPool;
+  Group: TProcThreadGroup;
+  ok: Boolean;
+  E: Exception;
+begin
+  Group:=Item.Group;
+  aPool:=Group.Pool;
+  ok:=false;
+  try
+    repeat
+      // work
+      Group.Run(Item.Index,Group.TaskData,Item);
+
+      aPool.EnterPoolCriticalSection;
+      try
+        Group.IndexComplete(Item.Index);
+
+        // find next work
+        if Group.LastRunningIndex<Group.EndIndex then begin
+          // next index of group
+          inc(Group.FLastRunningIndex);
+          Item.FIndex:=Group.FLastRunningIndex;
+        end else begin
+          // remove from group
+          RemoveFromList(Group.FFirstThread,mtptlGroup);
+          dec(Group.FThreadCount);
+          Item.FGroup:=nil;
+          Group:=nil;
+          if aPool.FFirstGroupNeedThreads<>nil then begin
+            // add to new group
+            aPool.FFirstGroupNeedThreads.AddThread(Self);
+            Group:=Item.Group;
+          end else begin
+            // mark inactive
+            RemoveFromList(aPool.FFirstActiveThread,mtptlPool);
+            AddToList(aPool.FFirstInactiveThread,mtptlPool);
+            Item.FState:=mtptsInactive;
+            RTLeventResetEvent(Item.fWaitForPool);
+          end;
+        end;
+      finally
+        aPool.LeavePoolCriticalSection;
+      end;
+      // wait for new work
+      if Item.FState=mtptsInactive then
+        RTLeventWaitFor(Item.fWaitForPool);
+    until Group=nil;
+    ok:=true;
+  except
+    // stop the exception and store it
+    E:=Exception(AcquireExceptionObject);
+    Terminating(aPool,E);
+  end;
+  if ok then
+    Terminating(aPool,nil);
+end;
+
+{ TProcThreadGroup }
+
+procedure TProcThreadGroup.AddToList(var First: TProcThreadGroup;
+  ListType: TMTPGroupState);
+begin
+  FNext:=First;
+  if FNext<>nil then
+    FNext.FPrev:=Self;
+  First:=Self;
+  FState:=ListType;
+end;
+
+procedure TProcThreadGroup.RemoveFromList(
+  var First: TProcThreadGroup);
+begin
+  if First=Self then
+    First:=FNext;
+  if FNext<>nil then
+    FNext.FPrev:=FPrev;
+  if FPrev<>nil then
+    FPrev.FNext:=FNext;
+  FNext:=nil;
+  FPrev:=nil;
+  FState:=mtpgsNone;
+end;
+
+function TProcThreadGroup.NeedMoreThreads: boolean;
+begin
+  Result:=(FLastRunningIndex<FEndIndex) and (FThreadCount<FMaxThreads)
+      and (FState<>mtpgsException);
+end;
+
+procedure TProcThreadGroup.AddThread(AThread: TProcThread);
+begin
+  AThread.Item.FGroup:=Self;
+  AThread.AddToList(FFirstThread,mtptlGroup);
+  inc(FThreadCount);
+  inc(FLastRunningIndex);
+  AThread.Item.FIndex:=FLastRunningIndex;
+  if not NeedMoreThreads then begin
+    RemoveFromList(Pool.FFirstGroupNeedThreads);
+    AddToList(Pool.FFirstGroupFinishing,mtpgsFinishing);
+  end;
+end;
+
+procedure TProcThreadGroup.RemoveThread(AThread: TProcThread);
+begin
+  AThread.RemoveFromList(FFirstThread,mtptlGroup);
+  dec(FThreadCount);
+end;
+
+procedure TProcThreadGroup.Run(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem); inline;
+begin
+  if Assigned(FTaskProcdure) then
+    FTaskProcdure(Index,Data,Item)
+  else
+    FTaskMethod(Index,Data,Item);
+end;
+
+procedure TProcThreadGroup.IndexComplete(Index: PtrInt);
+var
+  AThread: TProcThread;
+  NewFirstRunningThread: PtrInt;
+begin
+  // update FirstRunningIndex
+  NewFirstRunningThread:=FStarterItem.Index;
+  AThread:=FFirstThread;
+  while AThread<>nil do begin
+    if (NewFirstRunningThread>aThread.Item.Index)
+    and (aThread.Item.Index<>Index) then
+      NewFirstRunningThread:=aThread.Item.Index;
+    aThread:=aThread.FNext[mtptlGroup];
+  end;
+  FFirstRunningIndex:=NewFirstRunningThread;
+  // wake up threads (Note: do this even if FFirstRunningIndex has not changed)
+  WakeThreadsWaitingForIndex;
+end;
+
+procedure TProcThreadGroup.WakeThreadsWaitingForIndex;
+var
+  aThread: TProcThread;
+begin
+  if FState<>mtpgsException then begin
+    // wake up waiting threads
+    aThread:=FFirstThread;
+    while aThread<>nil do begin
+      if (aThread.Item.FState=mtptsWaitingForIndex)
+      and HasFinishedIndex(aThread.Item.WaitingForIndexStart,
+                           aThread.Item.WaitingForIndexEnd)
+      then begin
+        // wake up the thread
+        aThread.Item.FState:=mtptsActive;
+        RTLeventSetEvent(aThread.Item.fWaitForPool);
+      end;
+      aThread:=aThread.FNext[mtptlGroup];
+    end;
+    if (FStarterItem.FState=mtptsWaitingForIndex)
+    and HasFinishedIndex(FStarterItem.WaitingForIndexStart,FStarterItem.WaitingForIndexEnd)
+    then begin
+      // wake up the starter thread of this group
+      FStarterItem.FState:=mtptsActive;
+      RTLeventSetEvent(FStarterItem.fWaitForPool);
+    end;
+  end else begin
+    // end group: wake up waiting threads
+    aThread:=FFirstThread;
+    while aThread<>nil do begin
+      if (aThread.Item.FState=mtptsWaitingForIndex)
+      then begin
+        // end group: wake up the thread
+        aThread.Item.FState:=mtptsWaitingFailed;
+        RTLeventSetEvent(aThread.Item.fWaitForPool);
+      end;
+      aThread:=aThread.FNext[mtptlGroup];
+    end;
+    if (FStarterItem.FState=mtptsWaitingForIndex)
+    then begin
+      // end group: wake up the starter thread of this group
+      FStarterItem.FState:=mtptsWaitingFailed;
+      RTLeventSetEvent(FStarterItem.fWaitForPool);
+    end;
+  end;
+end;
+
+function TProcThreadGroup.HasFinishedIndex(
+  aStartIndex, aEndIndex: PtrInt): boolean;
+var
+  AThread: TProcThread;
+begin
+  // test the finished range
+  if FFirstRunningIndex>aEndIndex then exit(true);
+  // test the unfinished range
+  if FLastRunningIndex<aEndIndex then exit(false);
+  // test the active range
+  AThread:=FFirstThread;
+  while AThread<>nil do begin
+    if (AThread.Item.Index>=aStartIndex)
+    and (AThread.Item.Index<=aEndIndex) then
+      exit(false);
+    AThread:=AThread.FNext[mtptlGroup];
+  end;
+  if (FStarterItem.Index>=aStartIndex)
+  and (FStarterItem.Index<=aEndIndex) then
+    exit(false);
+  Result:=true;
+end;
+
+procedure TProcThreadGroup.EnterExceptionState(E: Exception);
+begin
+  if FState=mtpgsException then exit;
+  case FState of
+  mtpgsFinishing: RemoveFromList(Pool.FFirstGroupFinishing);
+  mtpgsNeedThreads: RemoveFromList(Pool.FFirstGroupNeedThreads);
+  end;
+  FState:=mtpgsException;
+  FException:=E;
+  WakeThreadsWaitingForIndex;
+end;
+
+constructor TProcThreadGroup.Create;
+begin
+  FStarterItem:=TMultiThreadProcItem.Create;
+  FStarterItem.FGroup:=Self;
+end;
+
+destructor TProcThreadGroup.Destroy;
+begin
+  FreeAndNil(FStarterItem);
+  inherited Destroy;
+end;
+
+{ TProcThreadPool }
+
+procedure TProcThreadPool.SetMaxThreadCount(const AValue: PtrInt);
+begin
+  if FMaxThreadCount=AValue then exit;
+  if AValue<1 then raise Exception.Create('TLightWeightThreadPool.SetMaxThreadCount');
+  FMaxThreadCount:=AValue;
+end;
+
+procedure TProcThreadPool.CleanTerminatedThreads;
+var
+  AThread: TProcThread;
+begin
+  while FFirstTerminatedThread<>nil do begin
+    AThread:=FFirstTerminatedThread;
+    AThread.RemoveFromList(FFirstTerminatedThread,mtptlPool);
+    AThread.Free;
+  end;
+end;
+
+constructor TProcThreadPool.Create;
+begin
+  FMaxThreadCount:=GetSystemThreadCount;
+  if FMaxThreadCount<1 then
+    FMaxThreadCount:=1;
+  InitCriticalSection(FCritSection);
+end;
+
+destructor TProcThreadPool.Destroy;
+
+  procedure WakeWaitingStarterItems(Group: TProcThreadGroup);
+  begin
+    while Group<>nil do begin
+      if Group.StarterItem.FState=mtptsWaitingForIndex then begin
+        Group.StarterItem.FState:=mtptsWaitingFailed;
+        RTLeventSetEvent(Group.StarterItem.fWaitForPool);
+      end;
+      Group:=Group.FNext;
+    end;
+  end;
+
+var
+  AThread: TProcThread;
+begin
+  FDestroying:=true;
+  // wake up all waiting threads
+  EnterPoolCriticalSection;
+  try
+    AThread:=FFirstActiveThread;
+    while AThread<>nil do begin
+      if aThread.Item.FState=mtptsWaitingForIndex then begin
+        aThread.Item.FState:=mtptsWaitingFailed;
+        RTLeventSetEvent(AThread.Item.fWaitForPool);
+      end;
+      AThread:=AThread.FNext[mtptlPool];
+    end;
+    WakeWaitingStarterItems(FFirstGroupNeedThreads);
+    WakeWaitingStarterItems(FFirstGroupFinishing);
+  finally
+    LeavePoolCriticalSection;
+  end;
+
+  // wait for all active threads to become inactive
+  while FFirstActiveThread<>nil do
+    Sleep(10);
+
+  // wake up all inactive threads (without new work they will terminate)
+  EnterPoolCriticalSection;
+  try
+    AThread:=FFirstInactiveThread;
+    while AThread<>nil do begin
+      RTLeventSetEvent(AThread.Item.fWaitForPool);
+      AThread:=AThread.FNext[mtptlPool];
+    end;
+  finally
+    LeavePoolCriticalSection;
+  end;
+
+  // wait for all threads to terminate
+  while FFirstInactiveThread<>nil do
+    Sleep(10);
+
+  // free threads
+  CleanTerminatedThreads;
+
+  DoneCriticalsection(FCritSection);
+  inherited Destroy;
+end;
+
+procedure TProcThreadPool.EnterPoolCriticalSection;
+begin
+  EnterCriticalsection(FCritSection);
+end;
+
+procedure TProcThreadPool.LeavePoolCriticalSection;
+begin
+  LeaveCriticalsection(FCritSection);
+end;
+
+procedure TProcThreadPool.DoParallel(const AMethod: TMTMethod;
+  StartIndex, EndIndex: PtrInt; Data: Pointer; MaxThreads: PtrInt);
+begin
+  if not Assigned(AMethod) then exit;
+  DoParallelIntern(AMethod,nil,StartIndex,EndIndex,Data,MaxThreads);
+end;
+
+procedure TProcThreadPool.DoParallel(const AProc: TMTProcedure;
+  StartIndex, EndIndex: PtrInt; Data: Pointer; MaxThreads: PtrInt);
+begin
+  if not Assigned(AProc) then exit;
+  DoParallelIntern(nil,AProc,StartIndex,EndIndex,Data,MaxThreads);
+end;
+
+procedure TProcThreadPool.DoParallelIntern(const AMethod: TMTMethod;
+  const AProc: TMTProcedure;
+  StartIndex, EndIndex: PtrInt; Data: Pointer; MaxThreads: PtrInt);
+var
+  Group: TProcThreadGroup;
+  i: PtrInt;
+  AThread: TProcThread;
+  NewThread: Boolean;
+  Item: TMultiThreadProcItem;
+  HelperThreadException: Exception;
+begin
+  if (StartIndex>EndIndex) then exit; // nothing to do
+  if FDestroying then raise Exception.Create('Pool destroyed');
+
+  if (MaxThreads>MaxThreadCount) or (MaxThreads<=0) then
+    MaxThreads:=MaxThreadCount;
+  if (StartIndex=EndIndex) or (MaxThreads<=1) then begin
+    // single threaded
+    Item:=TMultiThreadProcItem.Create;
+    try
+      for i:=StartIndex to EndIndex do begin
+        Item.FIndex:=i;
+        AMethod(i,Data,Item);
+      end;
+    finally
+      Item.Free;
+    end;
+    exit;
+  end;
+
+  // create a new group
+  Group:=TProcThreadGroup.Create;
+  Group.FPool:=Self;
+  Group.FTaskData:=Data;
+  Group.FTaskMethod:=AMethod;
+  Group.FTaskProcdure:=AProc;
+  Group.FStartIndex:=StartIndex;
+  Group.FEndIndex:=EndIndex;
+  Group.FFirstRunningIndex:=StartIndex;
+  Group.FLastRunningIndex:=StartIndex;
+  Group.FMaxThreads:=MaxThreads;
+  Group.FThreadCount:=1;
+  Group.FStarterItem.FState:=mtptsActive;
+  Group.FStarterItem.FIndex:=StartIndex;
+  HelperThreadException:=nil;
+  try
+    // start threads
+    EnterPoolCriticalSection;
+    try
+      Group.AddToList(FFirstGroupNeedThreads,mtpgsNeedThreads);
+      while Group.NeedMoreThreads do begin
+        AThread:=FFirstInactiveThread;
+        NewThread:=false;
+        if AThread<>nil then begin
+          AThread.RemoveFromList(FFirstInactiveThread,mtptlPool);
+        end else if FThreadCount<FMaxThreadCount then begin
+          AThread:=TProcThread.Create;
+          if Assigned(AThread.FatalException) then
+            raise AThread.FatalException;
+          NewThread:=true;
+          inc(FThreadCount);
+        end else begin
+          break;
+        end;
+        // add to Group
+        Group.AddThread(AThread);
+        // start thread
+        AThread.AddToList(FFirstActiveThread,mtptlPool);
+        AThread.Item.FState:=mtptsActive;
+        if NewThread then
+          AThread.Resume
+        else
+          RTLeventSetEvent(AThread.Item.fWaitForPool);
+      end;
+    finally
+      LeavePoolCriticalSection;
+    end;
+
+    // run until no more Index left
+    i:=StartIndex;
+    repeat
+      Group.FStarterItem.FIndex:=i;
+      Group.Run(i,Data,Group.FStarterItem);
+
+      EnterPoolCriticalSection;
+      try
+        Group.IndexComplete(i);
+        if (Group.FLastRunningIndex<Group.EndIndex) and (Group.FState<>mtpgsException)
+        then begin
+          inc(Group.FLastRunningIndex);
+          i:=Group.FLastRunningIndex;
+        end else begin
+          i:=StartIndex;
+        end;
+      finally
+        LeavePoolCriticalSection;
+      end;
+    until i=StartIndex;
+  finally
+    // wait for Group to finish
+    if Group.FFirstThread<>nil then begin
+      EnterPoolCriticalSection;
+      try
+        Group.FStarterItem.FState:=mtptsInactive;
+        Group.FStarterItem.fIndex:=EndIndex;// needed for Group.HasFinishedIndex
+        // wake threads waiting for starter thread to finish
+        if Group.FStarterItem.FState<>mtptsInactive then
+          Group.EnterExceptionState(nil)
+        else
+          Group.WakeThreadsWaitingForIndex;
+      finally
+        LeavePoolCriticalSection;
+      end;
+      // waiting with exponential spin lock
+      i:=0;
+      while Group.FFirstThread<>nil do begin
+        sleep(i);
+        i:=i*2+1;
+        if i>30 then i:=30;
+      end;
+    end;
+    // remove group from pool
+    EnterPoolCriticalSection;
+    try
+      case Group.FState of
+      mtpgsNeedThreads: Group.RemoveFromList(FFirstGroupNeedThreads);
+      mtpgsFinishing: Group.RemoveFromList(FFirstGroupFinishing);
+      end;
+    finally
+      LeavePoolCriticalSection;
+    end;
+    HelperThreadException:=Group.FException;
+    Group.Free;
+    // free terminated threads (terminated, because of exceptions)
+    CleanTerminatedThreads;
+  end;
+  // if the exception occured in a helper thread raise it now
+  if HelperThreadException<>nil then
+    raise HelperThreadException;
+end;
+
+initialization
+  ProcThreadPool:=TProcThreadPool.Create;
+
+finalization
+  ProcThreadPool.Free;
+  ProcThreadPool:=nil;
+
+end.
+
diff --git a/components/multithreadprocs/mtputils.pas b/components/multithreadprocs/mtputils.pas
new file mode 100644
index 000000000..4c5a6a857
--- /dev/null
+++ b/components/multithreadprocs/mtputils.pas
@@ -0,0 +1,200 @@
+{ Utilities using light weight threads.
+
+  This file is part of the Free Pascal run time library.
+
+  Copyright (C) 2008 Mattias Gaertner mattias@freepascal.org
+
+  See the file COPYING.FPC, included in this distribution,
+  for details about the copyright.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+{
+  Abstract:
+
+}
+unit MTPUtils;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, MTProcs;
+
+type
+
+  { TParallelSortPointerList }
+
+  TParallelSortPointerList = class
+  protected
+    fBlockSize: PtrInt;
+    fBlockCntPowOf2Offset: PtrInt;
+    FMergeBuffer: PPointer;
+    procedure MTPSort(Index: PtrInt; Data: Pointer; Item: TMultiThreadProcItem);
+  public
+    List: PPointer;
+    Count: PtrInt;
+    Compare: TListSortCompare;
+    BlockCnt: PtrInt;
+    constructor Create(aList: PPointer; aCount: PtrInt; const aCompare: TListSortCompare;
+                       MaxThreadCount: integer = 0);
+    procedure Sort;
+  end;
+
+procedure ParallelSortFPList(List: TFPList; const Compare: TListSortCompare;
+  MaxThreadCount: integer = 0);
+
+implementation
+
+procedure ParallelSortFPList(List: TFPList; const Compare: TListSortCompare;
+  MaxThreadCount: integer = 0);
+var
+  Sorter: TParallelSortPointerList;
+begin
+  if List.Count<=1 then exit;
+  Sorter:=TParallelSortPointerList.Create(@List.List[0],List.Count,Compare,
+                                          MaxThreadCount);
+  try
+    Sorter.Sort;
+  finally
+    Sorter.Free;
+  end;
+end;
+
+{ TParallelSortPointerList }
+
+procedure TParallelSortPointerList.MTPSort(Index: PtrInt; Data: Pointer;
+  Item: TMultiThreadProcItem);
+
+  procedure MergeSort(L, M, R: PtrInt; Recursive: boolean);
+  var
+    Src1: PtrInt;
+    Src2: PtrInt;
+    Dest1: PtrInt;
+  begin
+    if R-L<=1 then begin
+      // sort lists of 1 and 2 items directly
+      if L<R then begin
+        if Compare(List[L],List[R])>0 then begin
+          FMergeBuffer[L]:=List[L];
+          List[L]:=List[R];
+          List[R]:=FMergeBuffer[L];
+        end;
+      end;
+      exit;
+    end;
+    // sort recursively
+    if Recursive then begin
+      MergeSort(L,(L+M) div 2,M-1,true);
+      MergeSort(M,(M+R+1) div 2,R,true);
+    end;
+    // merge both blocks
+    Src1:=L;
+    Src2:=M;
+    Dest1:=L;
+    repeat
+      if (Src1<M)
+      and ((Src2>R) or (Compare(List[Src1],List[Src2])<=0)) then begin
+        FMergeBuffer[Dest1]:=List[Src1];
+        inc(Dest1);
+        inc(Src1);
+      end else if (Src2<=R) then begin
+        FMergeBuffer[Dest1]:=List[Src2];
+        inc(Dest1);
+        inc(Src2);
+      end else
+        break;
+    until false;
+    // write the mergebuffer back
+    Src1:=L;
+    Dest1:=l;
+    while Src1<=R do begin
+      List[Dest1]:=FMergeBuffer[Src1];
+      inc(Src1);
+      inc(Dest1);
+    end;
+  end;
+
+var
+  L, M, R: PtrInt;
+  i: integer;
+  NormIndex: Integer;
+  Range: integer;
+  MergeIndex: Integer;
+begin
+  L:=fBlockSize*Index;
+  R:=L+fBlockSize-1; // middle block
+  if R>=Count then
+    R:=Count-1; // last block
+  WriteLn('TParallelSortPointerList.LWTSort Index=',Index,' sort block: ',L,' ',(L+R+1) div 2,' ',R);
+  MergeSort(L,(L+R+1) div 2,R,true);
+
+  // merge
+  //  0 1 2 3 4 5 6 7
+  //  \/  \/  \/  \/
+  //    \/      \/
+  //        \/
+  // For example: BlockCnt = 5  => Index in 0..4
+  //   fBlockCntPowOf2Offset = 3  (=8-5)
+  //   NormIndex = Index + 3  => NormIndex in 3..7
+  i:=0;
+  NormIndex:=Index+fBlockCntPowOf2Offset;
+  repeat
+    Range:=1 shl i;
+    if NormIndex and Range=0 then break;
+    // merge left and right block(s)
+    MergeIndex:=NormIndex-Range-fBlockCntPowOf2Offset;
+    if (MergeIndex+Range-1>=0) then begin
+      // wait until left blocks have finished
+      WriteLn('TParallelSortPointerList.LWTSort Index=',Index,' wait for block ',MergeIndex);
+      if (MergeIndex>=0) and (not Item.WaitForIndex(MergeIndex)) then exit;
+      // compute left and right block bounds
+      M:=L;
+      L:=(MergeIndex-Range+1)*fBlockSize;
+      if L<0 then L:=0;
+      WriteLn('TParallelSortPointerList.LWTSort Index=',Index,' merge blocks ',L,' ',M,' ',R);
+      MergeSort(L,M,R,false);
+    end;
+    inc(i);
+  until false;
+  WriteLn('TParallelSortPointerList.LWTSort END Index='+IntToStr(Index));
+end;
+
+constructor TParallelSortPointerList.Create(aList: PPointer; aCount: PtrInt;
+  const aCompare: TListSortCompare; MaxThreadCount: integer);
+begin
+  List:=aList;
+  Count:=aCount;
+  Compare:=aCompare;
+  BlockCnt:=Count div 100; // at least 100 items per thread
+  if BlockCnt>ProcThreadPool.MaxThreadCount then
+    BlockCnt:=ProcThreadPool.MaxThreadCount;
+  if (MaxThreadCount>0) and (BlockCnt>MaxThreadCount) then
+    BlockCnt:=MaxThreadCount;
+  if BlockCnt<1 then BlockCnt:=1;
+end;
+
+procedure TParallelSortPointerList.Sort;
+begin
+  if (Count<=1) then exit;
+  fBlockSize:=(Count+BlockCnt-1) div BlockCnt;
+  fBlockCntPowOf2Offset:=1;
+  while fBlockCntPowOf2Offset<BlockCnt do
+    fBlockCntPowOf2Offset:=fBlockCntPowOf2Offset*2;
+  fBlockCntPowOf2Offset:=fBlockCntPowOf2Offset-BlockCnt;
+  WriteLn('TParallelSortPointerList.Sort BlockCnt=',BlockCnt,' fBlockSize=',fBlockSize,' fBlockCntPowOf2Offset=',fBlockCntPowOf2Offset);
+  GetMem(FMergeBuffer,SizeOf(Pointer)*Count);
+  try
+    ProcThreadPool.DoParallel(@MTPSort,0,BlockCnt-1);
+  finally
+    FreeMem(FMergeBuffer);
+    FMergeBuffer:=nil;
+  end;
+end;
+
+end.
+
diff --git a/components/multithreadprocs/multithreadprocslaz.lpk b/components/multithreadprocs/multithreadprocslaz.lpk
new file mode 100644
index 000000000..c3a150423
--- /dev/null
+++ b/components/multithreadprocs/multithreadprocslaz.lpk
@@ -0,0 +1,43 @@
+<?xml version="1.0"?>
+<CONFIG>
+  <Package Version="3">
+    <Name Value="MultiThreadProcsLaz"/>
+    <CompilerOptions>
+      <Version Value="8"/>
+      <SearchPaths>
+        <UnitOutputDirectory Value="lib/$(TargetCPU)-$(TargetOS)"/>
+      </SearchPaths>
+      <Other>
+        <CompilerPath Value="$(CompPath)"/>
+      </Other>
+    </CompilerOptions>
+    <Files Count="3">
+      <Item1>
+        <Filename Value="mtprocs.pas"/>
+        <UnitName Value="mtprocs"/>
+      </Item1>
+      <Item2>
+        <Filename Value="mtputils.pas"/>
+        <UnitName Value="mtputils"/>
+      </Item2>
+      <Item3>
+        <Filename Value="mtpcpu.pas"/>
+        <UnitName Value="mtpcpu"/>
+      </Item3>
+    </Files>
+    <Type Value="RunAndDesignTime"/>
+    <RequiredPkgs Count="1">
+      <Item1>
+        <PackageName Value="FCL"/>
+        <MinVersion Major="1" Valid="True"/>
+      </Item1>
+    </RequiredPkgs>
+    <UsageOptions>
+      <UnitPath Value="$(PkgOutDir)"/>
+    </UsageOptions>
+    <PublishOptions>
+      <Version Value="2"/>
+      <IgnoreBinaries Value="False"/>
+    </PublishOptions>
+  </Package>
+</CONFIG>
diff --git a/components/multithreadprocs/multithreadprocslaz.pas b/components/multithreadprocs/multithreadprocslaz.pas
new file mode 100644
index 000000000..098ebaeba
--- /dev/null
+++ b/components/multithreadprocs/multithreadprocslaz.pas
@@ -0,0 +1,20 @@
+{ This file was automatically created by Lazarus. do not edit!
+  This source is only used to compile and install the package.
+ }
+
+unit MultiThreadProcsLaz; 
+
+interface
+
+uses
+MTProcs, MTPUtils, MTPCPU, LazarusPackageIntf;
+
+implementation
+
+procedure Register; 
+begin
+end; 
+
+initialization
+  RegisterPackage('MultiThreadProcsLaz', @Register); 
+end.