Linux 太多打开的文件错误但 lsof 显示了合法数量的打开文件
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Too many open files error but lsof shows a legal number of open files
提问by hughw
My Java program is failing with
我的 Java 程序失败了
Caused by: java.io.IOException: Too many open files
at java.io.UnixFileSystem.createFileExclusively(Native Method)
at java.io.File.createNewFile(File.java:883)...
Here are key lines from /etc/security/limits.conf. They set the max files for a user at 500k:
以下是来自/etc/security/limits.conf. 他们将用户的最大文件数设置为 500k：
root soft nofile 500000
root hard nofile 500000
* soft nofile 500000
* hard nofile 500000
I ran lsofto to count the number of files open -- both globally and by the jvm process. I examined counters in /proc/sys/fs. All seems OK. My process only has 4301 files open and the limit is 500k:
我跑去lsof计算打开的文件数量——包括全局和 jvm 进程。我检查了/proc/sys/fs. 一切似乎都很好。我的进程只打开了 4301 个文件，限制为 500k：
:~# lsof | wc -l
5526
:~# lsof -uusername | wc -l
4301
:~# cat /proc/sys/fs/file-max
744363
:~# cat /proc/sys/fs/file-max
744363
:~# cat /proc/sys/fs/file-nr
4736 0 744363
This is an Ubuntu 11.04 server. I have even rebooted so I am positive these parameters are being used.
这是一个 Ubuntu 11.04 服务器。我什至重新启动，所以我肯定正在使用这些参数。
I don't know if it's relevant, but the process is started by an upstart script, which starts the process using setuidgid, like this:
我不知道它是否相关，但该过程是由一个 upstart 脚本启动的，该脚本使用 setuidgid 启动该过程，如下所示：
exec setuidgid username java $JAVA_OPTS -jar myprogram.jar
What I am missing?
我缺少什么？
采纳答案by hughw
It turns out the problem was that my program was running as an upstart init script, and that the execstanza does not invoke a shell. ulimitand the settings in limits.conf apply only to user processes in a shell.
事实证明，问题在于我的程序作为一个新贵的初始化脚本运行，并且该exec节没有调用 shell。ulimit并且limits.conf 中的设置仅适用于shell 中的用户进程。
I verified this by changing the exec stanza to
我通过将 exec 节更改为
exec sudo -u username java $JAVA_OPTS -jar program.jar
which runs java in username's default shell. That allowed the program to use as many open files as it needs.
它在用户名的默认 shell 中运行 java。这允许程序根据需要使用尽可能多的打开文件。
I have seen it mentionedthat you can also call ulimit -nprior to invoking the command; for an upstart script I think you would use a scriptstanza instead.
我看到它提到你也可以ulimit -n在调用命令之前调用；对于新贵脚本，我认为您会改用script节。
I found a better diagnostic than lsofto be ls /proc/{pid}/fd | wc -l, to obtain a precise count of the open file descriptor. By monitoring that I could see that the failures occurred right at 4096 open fds. I don't know where that 4096 comes from; it's not in /etc anywhere; I guess it's compiled into the kernel.
我找到了比lsof,更好的诊断方法ls /proc/{pid}/fd | wc -l，以获得打开文件描述符的精确计数。通过监控，我可以看到故障发生在 4096 个打开的 fds 处。我不知道 4096 是从哪里来的；它不在 /etc 任何地方；我猜它已编译到内核中。
回答by phs
I have this snippet of bash at the top of a server creation script:
我在服务器创建脚本的顶部有这个 bash 片段：
# Hyman up the max number of open file descriptors at the kernel
echo "fs.file-max = 1000000" >> /etc/sysctl.conf
invoke-rc.d procps start
# Increase max open file descriptors for this process
ulimit -n 1000000
# And for future ones as well
cat >> /etc/profile <<LIMITS
ulimit -n 1000000
LIMITS
cat >> /etc/security/limits.conf <<LIMITS
root - nofile 1000000
LIMITS
