服务器32G内存空间
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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