PGSQL优化后出错couldnotcreatesemaphores:Nospace

服务器32G内存空间

镇海ssl适用于网站、小程序/APP、API接口等需要进行数据传输应用场景，ssl证书未来市场广阔！成为创新互联的ssl证书销售渠道，可以享受市场价格4-6折优惠！如果有意向欢迎电话联系或者加微信：18982081108（备注：SSL证书合作）期待与您的合作！

参数优化

$ vi postgresql.conf

shared_buffers = 3072MB

max_connections = 4000

work_mem = 4MB

effective_cache_size = 4GB

maintenance_work_mem = 512MB 

wal_buffers = 256

具体优化参数解释参考：https://blog.csdn.net/zhousenshan/article/details/70233820

启动服务出错

$ pg_ctl -D /data/pg_data start

server starting

$ LOG:  could not create IPv6 socket: Address family not supported by protocol

FATAL:  could not create semaphores: No space left on device

DETAIL:  Failed system call was semget(5432124, 17, 03600).

HINT:  This error does *not* mean that you have run out of disk space.  It occurs when either the system limit for the maximum number of semaphore sets (SEMMNI), or the system wide maximum number of semaphores (SEMMNS), would be exceeded.  You need to raise the respective kernel parameter.  Alternatively, reduce PostgreSQL's consumption of semaphores by reducing its max_connections parameter.

        The PostgreSQL documentation contains more information about configuring your system for PostgreSQL.

LOG:  database system is shut down

分析：

这是因为内核参数中共享内存的配置限制了最大连接数，具体参考博客：https://www.cnblogs.com/xiaotengyi/p/5439231.html

解决办法：

# vi /etc/sysctl.conf

kernel.sem = 50100 128256000 50100 2560

重载配置

# sysctl -p

vm.min_free_kbytes = 409600

vm.vfs_cache_pressure = 200

vm.swappiness = 0

fs.file-max = 6815744

fs.aio-max-nr = 1048576

kernel.sysrq = 1

kernel.sem = 50100 128256000 50100 2560

net.core.rmem_default = 2621440

net.core.wmem_default = 2621440

net.core.rmem_max = 2621440

net.core.wmem_max = 2621440

net.ipv4.tcp_rmem = 4096        655360   2621440

net.ipv4.tcp_wmem = 4096        655360   2621440