Apache Child进程消耗大量内存

Question

"top" shows the result of how httpd-Child-process consume the memory. most Child process uses 400MB. I think this is too huge.

Usually, I know Child process consume the memory at most 50MB.

Do you know any good way to know why the child process uses huge memory?

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
1039 nobody    20   0 32.7g 412m  55m S  0.0  0.3   0:50.76 httpd
10366 nobody    20   0 32.7g 411m  54m S  0.0  0.3   1:11.28 httpd
16115 nobody    20   0 32.7g 410m  53m S  0.0  0.3   0:44.23 httpd
26472 nobody    20   0 32.7g 410m  52m S  0.0  0.3   0:45.95 httpd
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Answer 1

If the child processes are actively running and handling a large script, like a data import or something, then they might be holding a lot of data in memory while they run. It really depends on how scripts are running.

Typically, if Apache is handing off a request to a module like PHP or something (you have php as a tag on this question), it's the responsibility of that scripting engine to enforce some common-sense limits to things like memory usage or time limits to prevent people from creating scripts that try to suck up all the server's resources.

I would suggest trying to trace these child workers back to the specific requests to confirm that they are just out-of-control PHP scripts or something, then search the content of those scripts to see if they try to override any limits (like set_time_limit(0) or ini_set("memory_limit",...)). If they do, then you will have to talk to the developer of the scripts to figure out if they're really needed (eg maybe the developer is reading in a huge data file all at once and keeping it in memory instead of reading it in small chunks).