Summary:
The flakyness can be reproduced with the following patch:
```
--- a/db/db_impl_compaction_flush.cc
+++ b/db/db_impl_compaction_flush.cc
@@ -2013,6 +2013,9 @@ void DBImpl::BackgroundCallFlush() {
if (job_context.HaveSomethingToDelete()) {
PurgeObsoleteFiles(job_context);
}
+ static int f_count = 0;
+ printf("clean flush job context %d\n", ++f_count);
+ env_->SleepForMicroseconds(1000000);
job_context.Clean();
mutex_.Lock();
}
```
The issue is that FlushMemtable with opt.wait=true does not wait for `OnStallConditionsChanged` being called. The event listener is triggered on `JobContext::Clean`, which happens after flush result is installed. At the time we check for stall condition after flushing memtable, the job context cleanup may not be finished.
To fix the flaykyness, we use sync point to create a custom WaitForFlush that waits for context cleanup.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4658
Differential Revision: D13007301
Pulled By: yiwu-arbug
fbshipit-source-id: d98395ee7b0ad4c62e83e8d0e9b6028058c61712