CASSANDRA-21644 Fix concurrent SAI vector inserts failing once jvector's per-graph pool limit is exceeded - #5101
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…aph pool limit patch by Jeremiah Jordan; reviewed by XXX for CASSANDRA-21644
…ol limit is exceeded patch by Jeremiah Jordan; reviewed by XXX for CASSANDRA-21644
…urrent writers Review update: TrieMemtable and the locking ShardedSkipListMemtable serialize updates per shard, so when they have no more shards than jvector's per-builder limit there is nothing for the semaphore to bound. Add Memtable.limitsConcurrentWritesTo(int), false by default, and let OnHeapGraph leave the semaphore out when it is true. patch by Jeremiah Jordan; reviewed by XXX for CASSANDRA-21644
Review update: the mocked memtable always answered false to limitsConcurrentWritesTo(), so the tests never took the path where OnHeapGraph relies on the memtable and creates no semaphore. Have the mock answer according to the number of writer threads each test actually uses, so the tests within jvector's limit skip the semaphore and the test beyond it exercises it. The memtable implementations themselves are covered by MemtableConcurrentWriteLimitTest. Also the doc nit. patch by Jeremiah Jordan; reviewed by XXX for CASSANDRA-21644
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Fix concurrent SAI vector inserts failing once jvector's per-graph pool limit is exceeded.