Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming#86422
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azat merged 2 commits intoClickHouse:masterfrom Sep 1, 2025
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This place forgot to call background_memory_tracker.adjustOnBackgroundTaskEnd(), like we do for merges/mutations and this may lead to significant drift in MergesMutationsMemoryTracking, which later will lead to TOO_MANY_PARTS, because merges will stop. At first I actually added it (adjustOnBackgroundTaskEnd()) but later decided that it is wrong, merges/mutations should not take care about Buffer flushes. Note, maybe it will be a good idea to have a RAII for return value of createForBackgroundProcess() that will take care of adjustOnBackgroundTaskEnd(), but but this is not can be tricky since you need to make sure that there are no users of it (i.e. ThreadGroupSwitcher already finished).
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It has been removed in the previous patch from StorageBuffer::backgroundFlush(), but, it is required for query_views_log. So let's get it back, but in a more generic fashion.
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CheSema
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Sep 1, 2025
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| auto thread_group = ThreadGroup::createForBackgroundProcess(getContext()); |
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You wrote
/// For background tasks (i.e. Buffer flush) there may not be any group
But here thread group has been create for buffer flush. It did not match.
CheSema
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Any way, with that PR you create thread group for all the cases when there have not been thread group for current thread created yet.
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CI known and unrelated. |
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Cherry pick #86422 to 25.6: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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… and fix query_views_log for streaming
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Cherry pick #86422 to 25.7: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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… and fix query_views_log for streaming
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Cherry pick #86422 to 25.8: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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… and fix query_views_log for streaming
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Backport #86422 to 25.6: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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Backport #86422 to 25.7: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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Backport #86422 to 25.8: Fix leaking of MergesMutationsMemoryTracking and fix query_views_log for streaming
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Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):
Fix leaking of
MergesMutationsMemoryTrackingdue toBuffertables and fixquery_views_logfor streaming fromKafka(and others)For
Bufferwe started to usebackground_memory_trackersince #79963, but forgot to callbackground_memory_tracker.adjustOnBackgroundTaskEnd(), like we do for merges/mutations and this leads to drift inMergesMutationsMemoryTracking(significant one), which later will lead to TOO_MANY_PARTS, because merges will stop.At first I actually added it (
adjustOnBackgroundTaskEnd()) but later decided that it is wrong, merges/mutations should not take care aboutBufferflushes. Instead I've just created separateMemoryTrackerwithtotal_memory_trackeras parent, that does not requires such hacks. And this also fixesquery_views_logfor streaming fromKafka(and others), since previously there was noThreadGroupfor them.Note, maybe it will be a good idea to have a RAII for return value of createForBackgroundProcess() that will take care of adjustOnBackgroundTaskEnd(), but but this is not can be tricky since you need to make sure that there are no users of it (i.e. ThreadGroupSwitcher already finished).
Fixes: #79963 (cc @CheSema )
Fixes: #86398