Increase default pool_size

esl · Dec 16, 2021 · 19e818d · 19e818d
1 parent 95c9150
commit 19e818d
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diff --git a/doc/modules/mod_mam.md b/doc/modules/mod_mam.md
@@ -261,10 +261,10 @@ If the buffer is full, messages are flushed to a database immediately and the fl
 
 #### `modules.mod_mam_meta.async_writer.pool_size`
 * **Syntax:** non-negative integer
-* **Default:** `2 * erlang:system_info(schedulers_online)`
-* **Example:** `modules.mod_mam_meta.async_writer.pool_size = 30`
+* **Default:** `4 * erlang:system_info(schedulers_online)`
+* **Example:** `modules.mod_mam_meta.async_writer.pool_size = 32`
 
-Number of workers in the pool.
+Number of workers in the pool. More than the number of available schedulers is recommended, to minimise lock contention on the message queues, and more than the number of DB workers, to fully utilise the DB capacity. How much more than these two parameters is then a good fine-tuning for specific deployments.
 
 ### Common backend options
 

diff --git a/src/mam/mod_mam_rdbms_arch_async.erl b/src/mam/mod_mam_rdbms_arch_async.erl
@@ -72,7 +72,7 @@ add_callback(muc, Opts) ->
 defaults() ->
     #{flush_interval => 2000,
       batch_size => 30,
-      pool_size => 2 * erlang:system_info(schedulers_online)}.
+      pool_size => 4 * erlang:system_info(schedulers_online)}.
 
 prepare_insert_queries(pm, Opts) ->
     MaxSize = gen_mod:get_opt(batch_size, Opts, 30),

diff --git a/src/mongoose_async_pools.erl b/src/mongoose_async_pools.erl
@@ -84,7 +84,7 @@ gen_pool_name(HostType, PoolId) ->
 make_wpool_opts(HostType, PoolId, Opts) ->
     Interval = gen_mod:get_opt(flush_interval, Opts, 1000),
     MaxSize = gen_mod:get_opt(batch_size, Opts, 100),
-    NumWorkers = gen_mod:get_opt(pool_size, Opts, 2 * erlang:system_info(schedulers_online)),
+    NumWorkers = gen_mod:get_opt(pool_size, Opts, 4 * erlang:system_info(schedulers_online)),
     FlushCallback = gen_mod:get_opt(flush_callback, Opts),
     FlushExtra = make_extra(HostType, PoolId, Opts),
     ProcessOpts = [{message_queue_data, off_heap}],