问题描述
不常见，但有的时候开机redis没有自个启动，不知道如何查找原因，请高人指点
$ redis-cliCould not connect to Redis at 127.0.0.1:6379: Connection refused
我看了下日至，如下
[207] 29 Sep 18:22:41.020 * 1 changes in 900 seconds. Saving...[207] 29 Sep 18:22:41.099 * Background saving started by pid 2473[2473] 29 Sep 18:22:41.685 * DB saved on disk[207] 29 Sep 18:22:42.014 * Background saving terminated with success[207 | signal handler] (1380450274) Received SIGTERM, scheduling shutdown...[207] 29 Sep 18:24:34.759 # User requested shutdown...[207 | signal handler] (1380450274) Received SIGTERM, scheduling shutdown...[207] 29 Sep 18:24:34.899 * Saving the final RDB snapshot before exiting.[207] 29 Sep 18:24:35.050 * DB saved on disk[207] 29 Sep 18:24:35.050 * Removing the pid file.[207] 29 Sep 18:24:35.150 # Redis is now ready to exit, bye bye...[620] 29 Sep 21:50:35.953 * Max number of open files set to 10032_._ _.-``__ ’’-._ _.-`` `. `_. ’’-._ Redis 2.6.14 (00000000/0) 64 bit .-`` .-". "/ _.,_ ’’-._ ( ’ , .-` | `, ) Running in stand alone mode |`-._`-...-` __...-.``-._|’` _.-’| Port: 6379 | `-._ `._ / _.-’ | PID: 620 `-._ `-._ `-./ _.-’ _.-’ |`-._`-._ `-.__.-’ _.-’_.-’| | `-._`-.__.-’_.-’ | http://redis.io `-._ `-._`-.__.-’_.-’ _.-’ |`-._`-._ `-.__.-’ _.-’_.-’| | `-._`-.__.-’_.-’ | `-._ `-._`-.__.-’_.-’ _.-’ `-._ `-.__.-’ _.-’ `-.__.-’ `-.__.-’[620] 29 Sep 21:50:35.971 # Server started, Redis version 2.6.14[620] 29 Sep 21:50:35.984 * DB loaded from disk: 0.013 seconds[620] 29 Sep 21:50:35.984 * The server is now ready to accept connections on port 6379
好像也没有异常，上面提到的
[207] 29 Sep 18:24:35.050 * Removing the pid file.
因该是我关机的缘故，pid删除了，一般的情况下，开机会自动启动pid的，但是这次没有，上面启动界面是我最有一次手动启动的log信息
问题解答
回答1：redis在启动的时候会为信号SIGTERM注册信号处理函数，该函数会让redis在结束运行之前做些资源清理工作，譬如保存RDB文件，删除PID文件（如果redis是以daemon方式运行）等等，当这些工作都做完后，调用exit函数退出
所以日志这段内容：
[207 | signal handler] (1380450274) Received SIGTERM, scheduling shutdown...[207] 29 Sep 18:24:34.759 # User requested shutdown...[207 | signal handler] (1380450274) Received SIGTERM, scheduling shutdown...[207] 29 Sep 18:24:34.899 * Saving the final RDB snapshot before exiting.[207] 29 Sep 18:24:35.050 * DB saved on disk[207] 29 Sep 18:24:35.050 * Removing the pid file.[207] 29 Sep 18:24:35.150 # Redis is now ready to exit, bye bye.
都是符合上述我说的流程，收到SIGTERM信号 -> 处理资源 -> 结束redis服务
但是后面这些日志，看时间应该和上面的不是同一个：
[620] 29 Sep 21:50:35.953 * Max number of open files set to 10032
所以我觉得问题的关键是为什么在Redis启动的时候会收到一个SIGTERM信号?
