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Code Issues Releases Activity

Add 30 second wait loop to lockAcquire() when fail on no lock enabled.

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This should help prevent processes that are shutting down from interfering with processes that are starting up.
This commit is contained in:
David Steele
2018-01-17 15:03:55 -05:00
parent 1f39a34abc
commit a4c058d070
2 changed files with 22 additions and 6 deletions
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4
doc/xml/release.xml
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@@ -89,6 +89,10 @@
<p>Move lock release later in exitSafe() to reduce the chance of a new process starting and acquiring a lock before the old process has exited.</p>
</release-item>
<release-item>
<p>Add 30 second wait loop to lockAcquire() when fail on no lock enabled. This should help prevent processes that are shutting down from interfering with processes that are starting up.</p>
</release-item>
<release-item>
<p>Replace <code>cfgCommandTotal()</code>/<code>cfgOptionTotal()</code> functions with constants. The constants are applicable in more cases and allow the compiler to optimize certain loops more efficiently.</p>
</release-item>

24
lib/pgBackRest/Common/Lock.pm
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@@ -15,6 +15,7 @@ use File::Basename qw(dirname);
use pgBackRest::Common::Exception;
use pgBackRest::Common::Log;
use pgBackRest::Common::String;
use pgBackRest::Common::Wait;
use pgBackRest::Config::Config;
use pgBackRest::Storage::Helper;
@@ -91,17 +92,28 @@ sub lockAcquire
# Create the lock path
lockPathCreate();
# Attempt to open the lock file
# Loop until the lock can be acquired or timeout. This is to prevent race conditions where another process is shutting down
# but has not yet released its lock.
$strCurrentLockFile = lockFileName($strLockType, cfgOption(CFGOPT_STANZA, false), $bRemote);
my $oWait = waitInit(!defined($bFailOnNoLock) || $bFailOnNoLock ? 30 : 0);
sysopen($hCurrentLockHandle, $strCurrentLockFile, O_WRONLY | O_CREAT, oct(640))
or confess &log(ERROR, "unable to open lock file ${strCurrentLockFile}", ERROR_FILE_OPEN);
do
{
# Attempt to open the lock file
next if !sysopen($hCurrentLockHandle, $strCurrentLockFile, O_WRONLY | O_CREAT, oct(640));
# Attempt to lock the lock file
if (!flock($hCurrentLockHandle, LOCK_EX | LOCK_NB))
{
close($hCurrentLockHandle);
undef($hCurrentLockHandle);
}
}
while (!defined($hCurrentLockHandle) && defined($oWait) && waitMore($oWait));
# Attempt to lock the lock file
if (!flock($hCurrentLockHandle, LOCK_EX | LOCK_NB))
if (!defined($hCurrentLockHandle))
{
close($hCurrentLockHandle);
if (!defined($bFailOnNoLock) || $bFailOnNoLock)
{
confess &log(ERROR, "unable to acquire ${strLockType} lock on file ${strCurrentLockFile}", ERROR_LOCK_ACQUIRE);