问题
I installed MongoDB on Windows, Mac and Linux.
I run MongoDB with all default arguments and I enter a command db.serverStatus().connections on mongo to check the available connections.
Here is my observation, Windows 7 has 19999, Mac has only 203 and Linux has 818. Therefore, I would like to ask what makes the number of available connections different and is it possible to increase the available connections?
Thank you.
回答1:
For UNIX-like systems (i.e. Linux and OS X), the connection limit is governed by ulimits. MongoDB will use 80% of the available file descriptors for connections, which is why you see 203 on Mac (~80% of 256) and 819 on Linux (~80% of 1024).
The MongoDB documentation includes recommended settings for production systems. Typically you wouldn't need to change this on development environments, but you will see a warning on startup if the connection limits are considered low.
In MongoDB 2.4 and earlier, there is a hard-coded maximum of 20,000 connections per server irrespective of the ulimits. This maximum has been removed as at MongoDB 2.6.
There is also a maxConns MongoDB configuration directive that can be used to limit the connections to something lower than what would be allowed by ulimits.
回答2:
@fmchan Turn off SELinux and check again.
I set high NOFile and NProc limits on systemd, and in /etc/security/limits.conf file. But, it didn't help
Now, the only thing that works for me is to 1. setenforce 0 && systemctl restart mongod.service 2. Write a SELinux policy to allow mongod_exec_t to setrlimit and rlimitinh
Here's a similar issue https://bugzilla.redhat.com/show_bug.cgi?id=1415045
来源：https://stackoverflow.com/questions/22375027/mongodb-available-connections