Fix accounting for new/delete from different threads for VariableContext::Thread#16122
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azat wants to merge 1 commit intoClickHouse:masterfrom
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Fix accounting for new/delete from different threads for VariableContext::Thread#16122azat wants to merge 1 commit intoClickHouse:masterfrom
azat wants to merge 1 commit intoClickHouse:masterfrom
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…ext::Thread MemoryTracker assumes that for VariableContext::Thread new/delete may be called from different threads, hence the amount of memory can go negative. However the MemoryTracker is nested, so even if the negative amount is allowed for VariableContext::Thread it does not allowed for anything upper, and hence the MemoryTracking will not be decremented properly. Fix this, by looking at the initial level. This should fix memory drift for HTTP queries.
robot-clickhouse
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Don't understand how initial level can be anything other than thread.
I assume that memory tracking always goes via DB::CurrentThread::getMemoryTracker()
It means we don't need this branch anymore...
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Hm, nice catch, Ok, this PR will be replaced with these two patches from #16121:
- 17dcdaef751e2eaa60e6f5ed63779dfdafc81eaf
- 52d247f828c2c297dd4e4539b1f0d0876a53be15
(I can't push them separately since they are required to fix MemoryTracking, otherwise I can't write a test for that PR)
alexey-milovidov
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Oct 21, 2020
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Clarifications needed.
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Changelog category (leave one):
Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
Fix possible memory drift (due to new/delete from different threads)
Detailed description / Documentation draft:
MemoryTracker assumes that for VariableContext::Thread new/delete may be
called from different threads, hence the amount of memory can go
negative.
However the MemoryTracker is nested, so even if the negative amount is
allowed for VariableContext::Thread it does not allowed for anything
upper, and hence the MemoryTracking will not be decremented properly.
Fix this, by looking at the initial level.
Fixes: #15932 (This PR should fix memory drift for HTTP queries from that PR)
P.S. Marked as Improvement since backporting requirement is doubtful