Why can there be a long server response?

Question

linux

Today I noticed that the sites began to give the page longer than usual, I immediately thought maybe it was a long SQL or something like that, I went to look, but the requests were normal, I measured the page generation time using microtime, it was no more than 0.01, but some pages were loading at 12 seconds, for reliability, I also rebooted the server, but the problem did not disappear, and it is not constant, but comes in waves, for 3 minutes everything freezes for 2 minutes, the flight is normal, and so on, in which direction to dig? Where can you find the reason?
An example of loading a page from

chroma

Answer 1

in this case, most likely, you are using prefork as a multiprocessor module and you have this limit on the number of running httpd processors and are waiting for their release to process the request. Try looking in the configuration files for a `` or ` ` block and increase the value for the MaxClients and ServerLimit parameters in them.