我有两个spring应用程序，在这两个应用程序中我都使用spymmacached。memcached客户端是这样创建的
private MemcachedClient buildClient() {
String address = this.serverAddress;
MemcachedClient result;
if (StringUtils.isNotEmpty(address)) {
log.info("connecting to memcached server {}", address);
try {
result = new MemcachedClient(
new ConnectionFactoryBuilder()
.setTranscoder(new CustomSerializingTranscoder())
.setProtocol(protocol)
.setTimeoutExceptionThreshold(2)
.build(),
AddrUtil.getAddresses(address));
} catch (IOException e) {
throw new IllegalStateException("Can't create client", e);
}
log.info("connected to memcached server {}", address);
} else {
log.warn("cannot initialize memcached client: memcached address is not set");
result = null;
}
return result;
}
一个spring-app put(总是替换一个(key:value在memcached中。另一个读这把钥匙。与读取值的应用程序不断断开连接。
Memcached配置：
[r.gomboev@netris-gps-stage60-01 netris]$ sudo systemctl status memcached
● memcached.service - Memcached
Loaded: loaded (/usr/lib/systemd/system/memcached.service; enabled; vendor preset: disabled)
Active: active (running) since Пн 2022-01-24 18:29:39 MSK; 1 day 1h ago
Main PID: 16747 (memcached)
Tasks: 6
Memory: 18.9M
CGroup: /system.slice/memcached.service
└─16747 /usr/bin/memcached -u memcached -p 11211 -m 64 -c 1024 -vv
但问题是memcached服务器不断断开连接。
memcached日志：
Jan 25 13:21:50 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 13:22:44 memcached-server-01 memcached: <33 connection closed.
Jan 25 13:23:19 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 13:23:33 memcached-server-01 memcached: <33 connection closed.
Jan 25 13:23:55 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 13:26:34 memcached-server-01 memcached: <33 connection closed.
Jan 25 13:31:36 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 13:45:03 memcached-server-01 memcached: <33 connection closed.
Jan 25 16:11:43 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 18:45:12 memcached-server-01 memcached: <33 connection closed.
Jan 25 19:39:36 memcached-server-01 memcached: <33 new auto-negotiating client connection
Jan 25 19:41:11 memcached-server-01 memcached: <33 connection closed.
当我通过lsof 查看连接时
on app server 81.166
[user@test-dmz-02 ~]$ sudo lsof -i -P -n | grep 11211 | grep 82.80
java 12150 cctv 90u IPv6 1037210363 0t0 TCP 10.200.81.166:35742->10.200.82.80:11211 (ESTABLISHED)
connection established
but on memcached server 82.80
[user@memcached-server-01]$ sudo lsof -i -P -n | grep 11211 | grep 81.166
no connection
memcached有下一个统计
Escape character is '^]'.
stats
STAT pid 16747
STAT uptime 93258
STAT time 1643131435
STAT version 1.4.15
STAT libevent 2.0.21-stable
STAT pointer_size 64
STAT rusage_user 10.729242
STAT rusage_system 17.056611
STAT curr_connections 15
STAT total_connections 62
STAT connection_structures 20
STAT reserved_fds 20
STAT cmd_get 738
STAT cmd_set 84624
STAT cmd_flush 0
STAT cmd_touch 0
STAT get_hits 737
STAT get_misses 1
STAT delete_misses 0
STAT delete_hits 0
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 156369146
STAT bytes_written 100524068
STAT limit_maxbytes 67108864
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 0
STAT hash_power_level 16
STAT hash_bytes 524288
STAT hash_is_expanding 0
STAT bytes 85
STAT curr_items 1
STAT total_items 84623
STAT expired_unfetched 0
STAT evicted_unfetched 0
STAT evictions 0
STAT reclaimed 0
END
我找不到memcached服务器关闭连接的原因触发器。有人能告诉我找到解决方案的方法吗？谢谢
我找到了原因。unix系统关闭了空闲的tcp连接。参数在文件/proc/sys/net/ipv4/tcp_keepalive_time中，单位为秒
cat /proc/sys/net/ipv4/tcp_keepalive_time
7200
作为解决方案，如果第一次尝试失败，我会尝试另一次连接到memcached。