Space may not be reclaimed if locks are not available after three retries (code
inspection)
-------------------------------------------------------------------------------------------
Key: DERBY-4055
URL: https://issues.apache.org/jira/browse/DERBY-4055
Project: Derby
Issue Type: Bug
Components: Store
Affects Versions: 10.4.2.0, 10.3.3.0, 10.2.2.0, 10.1.3.1, 10.5.0.0
Reporter: Kathey Marsden
Priority: Minor
I don't have a reproduction for these cases but there are two places in
ReclaimSpaceHelper where reclamation will give up after three tries if it
cannot obtain the lock to reclaim the space. The first code path is:
ContainerHandle containerHdl =
openContainerNW(tran, container_rlock,
work.getContainerId());
if (containerHdl == null)
{
tran.abort();
if (SanityManager.DEBUG)
{
if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
{
SanityManager.DEBUG(
DaemonService.DaemonTrace, " aborted " + work +
" because container is locked or dropped");
}
}
if (work.incrAttempts() < 3) // retry this for serveral
times
{
return Serviceable.REQUEUE;
}
else
{
// If code gets here, the space will be lost forever, and
// can only be reclaimed by a full offline compress of the
// table/index.
if (SanityManager.DEBUG)
{
if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
{
SanityManager.DEBUG(
DaemonService.DaemonTrace,
" gave up after 3 tries to get container lock " +
work);
}
}
return Serviceable.DONE;
}
}
the second is:
RecordHandle headRecord = work.getHeadRowHandle();
if (!container_rlock.lockRecordForWrite(
tran, headRecord, false /* not insert */, false /* nowait */))
{
// cannot get the row lock, retry
tran.abort();
if (work.incrAttempts() < 3)
{
return Serviceable.REQUEUE;
}
else
{
// If code gets here, the space will be lost forever, and
// can only be reclaimed by a full offline compress of the
// table/index.
if (SanityManager.DEBUG)
{
if (SanityManager.DEBUG_ON(DaemonService.DaemonTrace))
{
SanityManager.DEBUG(
DaemonService.DaemonTrace,
" gave up after 3 tries to get row lock " +
work);
}
}
return Serviceable.DONE;
}
}
If working to get a reproduction for these cases, you can set
derby.debug.true=DaemonTrace and look for "gave up" in the derby.log.
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