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:
#
#<domain> <type> <item> <value>
#
#Where:
#<domain> 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
#
#<type> can have the two values:
# - "soft" for enforcing the soft limits
# - "hard" for enforcing hard limits
#
#<item> 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
#
#<domain> <type> <item> <value>
#
#* 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