linux修改POSIX消息队列（msgqueue）的各项限制（最大内存、msg_max、msgsize_max、queues_max）

1.进入 目录 /proc/sys/fs/mqueue/，查看各项消息队列的默认max设置：

[root@localhost ~]# ls -l /proc/sys/fs/mqueue/
total 0
-rw-r--r-- 1 root root 0 Aug 20 23:04 msg_default
-rw-r--r-- 1 root root 0 Aug 20 23:04 msg_max
-rw-r--r-- 1 root root 0 Aug 20 23:04 msgsize_default
-rw-r--r-- 1 root root 0 Aug 20 23:04 msgsize_max
-rw-r--r-- 1 root root 0 Aug 20 23:04 queues_max
[root@localhost ~]# cat  /proc/sys/fs/mqueue/msg_max
10
[root@localhost ~]# cat  /proc/sys/fs/mqueue/msgsize_max
8192
[root@localhost ~]# cat  /proc/sys/fs/mqueue/queues_max
256

以修改msg_max为例：

[root@localhost ~]# echo "10000">/proc/sys/fs/mqueue/msg_max
[root@localhost ~]# cat  /proc/sys/fs/mqueue/msg_max
10000

上述可解决mq_open时，经常遇到的errno=22：/* Invalid argument */问题，其他修改类型。

2. 解除消息队列占用内存81920的限制：

vim  /etc/security/limits.conf

添加：

*       soft    msgqueue        unlimited
*       hard    msgqueue        unlimited

上述各列用tab分开，保存后系统重新启动后生效。使用下面命令验证：

[root@localhost ~]# ulimit -q
unlimited

附，/etc/security/limits.conf文件的说明：

[root@localhost ~]# cat /etc/security/limits.conf
# /etc/security/limits.conf
#
#This file sets the resource limits for the users logged in via PAM.
#It does not affect resource limits of the system services.
#
#Also note that configuration files in /etc/security/limits.d directory,
#which are read in alphabetical order, override the settings in this
#file in case the domain is the same or more specific.
#That means for example that setting a limit for wildcard domain here
#can be overriden with a wildcard setting in a config file in the
#subdirectory, but a user specific setting here can be overriden only
#with a user specific setting in the subdirectory.
#
#Each line describes a limit for a user in the form:
#
#            
#
#Where:
# can be:
#        - a user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#        - the wildcard %, can be also used with %group syntax,
#                 for maxlogin limit
#
# can have the two values:
#        - "soft" for enforcing the soft limits
#        - "hard" for enforcing hard limits
#
# can be one of the following:
#        - core - limits the core file size (KB)
#        - data - max data size (KB)
#        - fsize - maximum filesize (KB)
#        - memlock - max locked-in-memory address space (KB)
#        - nofile - max number of open file descriptors
#        - rss - max resident set size (KB)
#        - stack - max stack size (KB)
#        - cpu - max CPU time (MIN)
#        - nproc - max number of processes
#        - as - address space limit (KB)
#        - maxlogins - max number of logins for this user
#        - maxsyslogins - max number of logins on the system
#        - priority - the priority to run user process with
#        - locks - max number of file locks the user can hold
#        - sigpending - max number of pending signals
#        - msgqueue - max memory used by POSIX message queues (bytes)
#        - nice - max nice priority allowed to raise to values: [-20, 19]
#        - rtprio - max realtime priority
#
#                 
#

#*               soft    core            0
#*               hard    rss             10000
#@student        hard    nproc           20
#@faculty        soft    nproc           20
#@faculty        hard    nproc           50
#ftp             hard    nproc           0
#@student        -       maxlogins       4