Solution to excessive memory usage on linux servers

Today, a friend asked me why the linux server's memory usage is too high. Is there a way to solve this problem? Next I will introduce to you how to solve this problem, I hope this method will help you.

Today, the company has checked the status of all servers and found that memory usage of one server is much larger than normal, such

Qq immediately asked if the program development had changed something in the last two days. When I learned that nothing had been changed, I immediately restarted php-fpm and nginx, after the restart, check that the memory has been released for 1 GB, but this is not enough, because this server is 8 GB of memory and usually uses a maximum of 4 GB memory, I want to use more than 7 GB of server memory today, but it is obviously abnormal. Continue to check.

During the check, I used the top command to check which process occupies the largest memory. I did not find anything in the last minute. Then I used the command to check the top 10 processes with the largest memory usage:

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Ps-aux | sort-k4nr | head-n 10

It only shows that nginx and php-fpm occupy the largest memory, but I restarted these two processes. It seems that they have nothing to do with them. I began to wonder if the server was hacked, check the ps aux process immediately. This check shows the problem. There are many scripts generated in the process. Run the following command to kill them immediately:

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Kill-9 $ (ps aux | grep process name | grep-v grep | awk '{print $2 }')

Now we can see the memory usage, and the memory is still working properly. Now, let's take a few minutes and exit the server. Check the script again.

Ps: the things to be emphasized here should not be simply thought of as what the problem is based on your own intuition. It is best to investigate and execute it again, for example, I thought it was a problem with nginx and php-fpm based on my intuition. Fortunately, I had to say hello to the boss and restart it. Otherwise, the consequences would be very serious.

Run the following command to check the process with the largest memory usage:

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Ps aux | grep-v "USER" | sort-n-r-k 4 | awk 'nr = 1 {print $0 }'

I am using a php script. Here we wrote a linux script for restarting php when the linux load is too high.

You can restart php based on your server load. I only set the server load to 1 and restart php.

System: centos 5.9 64-bit
Script content:
Vi check-php.sh

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#! /Bin/sh TOP_SYS_LOAD_NUM = 1 SYS_LOAD_NUM = 'uptime | awk' {print $ (NF-2)} '| sed's /,//'' Echo $ (date + "% y-% m-% d") 'uptime' If ['echo "$ TOP_SYS_LOAD_NUM <$ SYS_LOAD_NUM" | bc '-eq 1] Then Echo "#0 #" $ (date + "% y-% m-% d % H: % M: % S ") "pkill php-fpm" 'ps-ef | grep php-fpm | wc-l' /Etc/init. d/php-fpm stop Sleep 8 Pkill php-fpm Sleep 8 For I in 1 2 3 Do If ['pgrep php-fpm | wc-l'-le 0] Then /Etc/init. d/php-fpm start Sleep 30 Echo "#1 #" $ (date + "% y-% m-% d % H: % M: % S ") "start php-fpm" 'ps-ef | grep php-fpm | wc-l' Fi Done Else If ['pgrep php-fpm | wc-l'-le 0] Then /Etc/init. d/php-fpm start Sleep 30 Echo "#2 #" $ (date + "% y-% m-% d % H: % M: % S ") "start php-fpm" 'ps-ef | grep php-fpm | wc-l' Fi Fi

Scheduled execution

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*/3 */root/shell/check-php.sh>/var/log/check-php.log

If you run the script:

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: Line 6: bc: command not found : Line 6: [:-eq: unary operator expected

Indicates that no bc command is available. centos can be installed using yum-y install bc.