SBLK_MASK_LOCK_THREADID allow tid up to 65535 (#88772) #89335
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* SBLK_MASK_LOCK_THREADID allow tid up to 65535 * copy comment from NativeAOT ObjectHeader.cs --------- Co-authored-by: dickens <[email protected]>
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Friendly reminder: if you want this servicing fix to be included in the September 2023 Release, you'll have to merge this PR before August 14th. |
Maoni0
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Aug 3, 2023
jeffschwMSFT
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Aug 9, 2023
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Customer Impact - from @dickens-code
Our apps require low latency performance and we are trying hard to reduce memory allocation in order to minimise GC occurrences.
We noticed that one of our apps experiences a very long GC pause of 2 seconds, and with the help of @cshung, we discovered that our app is having very large sync block memory space (20 million sync blocks), which introduced a very long time of sync block scanning during GC events.
We found out that new sync blocks are introduced when thread ID > 1024 is taking object locks and we tried to release the limit of thread ID to 65535 and the sync block memory space size was obviously improved
With the custom-built
coreclr.dllwe observed that our app's GC pauses were brought down to around 100ms which makes more sense according to our business requirementsTesting
Test failures are known - on my machine, I don't have sufficient memory to pass the 20GB large pages test case, all other large page test cases are passing.
Risk
Low - the bits were not used for anything before this fix, and the change is merged to main for 2 weeks with no regression found.