Unable to fork new process in Linux/Unix

Products

• VMware
• Support Only for Apache HTTP

Issue/Introduction

Symptoms:

• Unable to fork a new process in Linux/Unix.
• The error log contains the error:
  
  [error] (12)Not enough space: fork: Unable to fork new process
  
  
• The server is unable to handle additional connections.

Environment

VMware vFabric Enterprise Ready Server 4
Apache HTTP Server 2.2
Apache HTTP Server 2.0

Cause

This issue occurs when the system has run out of file handles, which prevents the httpd process from creating the necessary number of processes if you are using the prefork MPM.

Resolution

To resolve this issue, increase the number of file descriptors available to httpd.

To check the number of hard and soft file descriptors available on the system, run the command:

ulimit -n

To increase the number of file descriptors available to httpd, run the command:

ulimit -n number

Where number is the number of file descriptors available to httpd

For example:

ulimit -n 2048

Contact your operating system provider for more information about file descriptors and the ulimit command.

Note: This command can be added to a system startup file or the apache_startup.sh script for the affected instance.