[Improvement](fragment) Use partitioned hash map to manage contexts (a…

…pache#46235)

Contexts in `fragment_mgr` are managed by a global map and accessed by
multiple threads concurrently with a global lock. It introduced a
obvious overhead. To solve it , this PR use a partitioned hash table to
optimize the global lock.

be/src/common/config.cpp

@@ -211,6 +211,7 @@ DEFINE_Int32(check_consistency_worker_count, "1");
 DEFINE_Int32(upload_worker_count, "1");
 // the count of thread to download
 DEFINE_Int32(download_worker_count, "1");
+DEFINE_Int32(num_query_ctx_map_partitions, "128");
 // the count of thread to make snapshot
 DEFINE_Int32(make_snapshot_worker_count, "5");
 // the count of thread to release snapshot

be/src/common/config.h

@@ -1350,6 +1350,8 @@ DECLARE_Int32(spill_io_thread_pool_queue_size);
 
 DECLARE_mBool(check_segment_when_build_rowset_meta);
 
+DECLARE_Int32(num_query_ctx_map_partitions);
+
 DECLARE_mBool(enable_s3_rate_limiter);
 DECLARE_mInt64(s3_get_bucket_tokens);
 DECLARE_mInt64(s3_get_token_per_second);