what's the role of ShardingTaskExecutorPoolMaxSize and taskExecutorPoolSize

[陈小生]

as the official documents:

ShardingTaskExecutorPoolMaxSize

Maximum number of outbound connections each TaskExecutor connection pool can open to any given mongod instance. The maximum possible connections to any given host across all TaskExecutor pools is:

ShardingTaskExecutorPoolMaxSize * taskExecutorPoolSize

I try to run mongos as below:

bin/mongos --config --setParameter taskExecutorPoolSize=4 --setParameter ShardingTaskExecutorPoolMaxSize=3

According to the docs and my understanding, the connections from mongos to mongod shoould be 4*3=12?

but after test, i got different results:

1. my client conect to mongos with 60 connections;

2. mongos connect to a mongod with 2 rs

mongos to rs1 have 48 connections.

mongos to rs2 have 59 connections.

so, what is the real mean for these two settings? or I have a wrong settings?

Thanks.