OOM Killer Resolutions: Processes with High Risk of Memory Leak

Pay special attention to the processes in this group as to the most probable cause of your out-of-memory issues (sorted based on server role):

• Load Balancers
• Application Servers
• Database Servers
• Common Processes for Different-Type Stacks

Load Balancers

Common recommendations

Allocate more RAM to a corresponding node - handled services could just require more memory for normal operability.

Related processes

Application Servers

Click on points within the list below to view some common recommendations on dealing with memory shortage issues considering used programming language, as well as appropriate resolutions for the most demanding related processes:

• Java

  Common recommendations

  Review the main memory management configurations for your Java machine and, if required, adjust them according to your application needs, e.g.:

  java -Xmx2048m -Xms256m

  where

  • Xmx flag specifies the maximum heap memory that could be allocated for a Java Virtual Machine (JVM)
  • Xms flag defines initial memory allocation pool

  Refer to the official documentation for more info on Java memory management system.

  Tip: The platform also implements supplementary automated memory management for Java containers using Garbage Collector. You are able to customize its settings considering your application specifics to avoid OOM issues and gain more efficient memory utilization.

  Also, take into consideration, that JVM needs more memory than just heap - read through Java Memory Structure reference to get deeper insights.

  Related processes

  Process	Resolution
  java	Check the xmx, xms, xmn parameters of your Java machine and configure them according to your application needs

• PHP

  Common recommendations

  1. If the problem occurs with the httpd (httpd.itk) service, adjust server memory management parameters as follows:

  • check the average amount of RAM, used by each httpd instance
  • remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file
  • decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM

  Note: In case you note persistent growth of memory usage per instance (leak), you need to decrease the MaxRequestsPerChild value (to around 1000-5000).

  2. For the nginx process, connect to your container via SSH and check the size of php-fpm instances (e.g. with ps or top tools):

  • if all of them consume ~50-100Mb of RAM, disable auto configuration and decrease the max_children parameter
  • if instances size varies greatly or is over 200-300Mb, the process is probably leaking - inspect and optimize your code or, alternatively, disable auto configuration and decrease the max_requests_per_child parameter

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  lsyncd	Allocate more RAM to a node - handled services could just require more memory for normal operability
  httpd.itk	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  nginx	Disable Jelastic auto configuration and adjust the appropriate parameters according to your application specifics
  php	Disable Jelastic auto configuration and adjust the appropriate parameters according to your application specifics
  php-fpm	Disable Jelastic auto configuration and adjust the appropriate parameters according to your application specifics
  php-fpm7.0	Disable Jelastic auto configuration and adjust the appropriate parameters according to your application specifics
  php7.0	Disable Jelastic auto configuration and adjust the appropriate parameters according to your application specifics

• Ruby

  Common recommendations

  Memory leak issues are rather common for Ruby, so, as the first thing to do, consider to inspect and optimize your code. Alternatively, try to increase RAM limit for an instance.

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  httpd.itk	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  bundle	Allocate more RAM to a node - handled services could just require more memory for normal operability
  gem	Allocate more RAM to a node - handled services could just require more memory for normal operability
  ruby	Consider to inspect and optimize your code or add more RAM to a node

• Python

  Common recommendations

  1. If the problem occurs with the httpd (httpd.itk) service, adjust server memory management parameters as follows:

  • check the average amount of RAM, used by each httpd instance
  • remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file
  • decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM

  Note: In case you note persistent growth of memory usage per instance (leak), decrease the MaxRequestsPerChild value (to around 1000-5000).

  2. Otherwise, allocate more RAM to a node - the main Python process could just require more memory for normal operability.

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  lsyncd	Allocate more RAM to a node - handled application could just require more memory for normal operability
  httpd.itk	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  pip	Can be caused by network issues (so that the download process stucks); otherwise, allocate more RAM to a node - handled application could just require more memory for normal operability
  python	Allocate more RAM to a node - handled application could just require more memory for normal operability
  python2.7	Allocate more RAM to a node - handled application could just require more memory for normal operability

• NodeJS

  Common recommendations

  Restart container to restore the killed process(es). If the issue repeats, allocate more RAM to a node - handled application could just require more memory for normal operability.

  Related processes

  Process	Resolution
  lsyncd	Allocate more RAM to a node - handled application could just require more memory for normal operability
  grunt	Allocate more RAM to a node - handled application could just require more memory for normal operability
  node	Allocate more RAM to a node - handled application could just require more memory for normal operability
  npm	Allocate more RAM to a node - handled application could just require more memory for normal operability
  phantomjs	Allocate more RAM to a node - handled application could just require more memory for normal operability

Database Servers

Click on the required DB stack within the list below to reveal appropriate common recommendations on coping with OOM issues, as well as resolutions for particular killed processes:

• MySQL

  Common recommendations

  1. If using InnoDB engine (embedded since 5.5 MySQL version), check buffers size with the next command:

  SHOW ENGINE INNODB STATUS\G;

  In case of high buffers value (over 80% of total container RAM), reduce size of the allowed pool with the innodb_buffer_pool_size parameter in /etc/my.cnf file; otherwise, allocate more RAM to a server.

  2. Also, check MySQL logs for warnings and recommendations.

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  mysqld	1. If using InnoDB engine (by default for MySQL 5.5 and higher), check buffers size with the SHOW ENGINE INNODB STATUS\G; command. In case of high buffers value (over 80% of total container RAM), reduce the allowed pool size with the innodb_buffer_pool_size parameter in /etc/my.cnf file 2. Check MySQL logs for warnings and recommendations

• MongoDB

  Common recommendations

  If the problem occurs with the httpd service, adjust server memory management parameters as follows:

  • check the average amount of RAM, used by each httpd instance
  • remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file
  • decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM

  Note: In case you note persistent growth of memory usage per instance (leak), decrease the MaxRequestsPerChild value (to around 1000-5000).

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  mongod	Allocate more RAM to a node - handled services could just require more memory for normal operability

• PostgreSQL

  Common recommendations

  Allocate more RAM to a corresponding node - handled services could just require more memory for normal operability.

  Related processes

  Process	Resolution
  httpd	1. Check the average amount of RAM, used by each httpd instance 2. Remove the Jelastic autoconfiguration mark within the /etc/httpd/httpd.conf file 3. Decrease ServerLimit and MaxClients values according to the formula: (Total_RAM - 5%) / Average_RAM
  postgres	Allocate more RAM to a node - handled services could just require more memory for normal operability

• Redis

  Common recommendations

  Allocate more RAM to a corresponding node - handled services could just require more memory for normal operability.

  Related processes

  Process	Resolution
  redis-server	Allocate more RAM to a node - handled services could just require more memory for normal operability

Common Processes for Different-Type Stacks

Common recommendations

Processes in this section can be run and, subsequently, killed within different node types. Thus, OOM resolutions for them vary and depend on a process itself - see the table below to find the appropriate recommendations.

Related processes

What’s next?

• OOM Killer Troubleshooting
• Common Cases
• Non-Leaking Processes
• Java Garbage Collection
• PHP Auto Configuration