6.3.5. Instance parameters — general

To modify instance parameters, select Zorp > Instance > Edit parameters.

The following generic settings can be configured for those instance parameters that are Active/Enabled, consequently are visible in dark colour. Inactive/Disabled instance parameters are listed in light grey:

  • Instance: It is the name of the instance.

  • Stop instance before rename: When renaming an instance and this option is enabled, Zorp stops the instance, renames it, then starts the renamed instance.

  • Description: The user can provide a description of the instance here.

The General tab has the following parameters:

General instance parameters

Figure 6.19. General instance parameters

  • Thread limit: It is the number of threads the instance can start. Set Thread limit according to the anticipated number of concurrent connections. Most of the active client requests require their own thread. If the Thread limit is too low, the clients will experience delays and refused connection attempts.

  • Number of processes: It reflects the number of Zorp processes the instance can start. This setting determines the number of CPU cores that the instance can use. If our Zorp host has many CPUs, increase this value for instances that have high traffic. Note that the Thread limit and the Thread stack limit parameters are applied separately for each process. For details on increasing the number of running processes, see Procedure 6.3.9, Increasing the number of running processes.

    For every process, Zorp uses a certain amount of memory from the stack. At most, a process uses the default value of the stack size of the host (which is currently 8 MB for Ubuntu 18.04 LTS). Zorp uses this memory only when it is actually needed by the thread, it is not allocated in advance. Note that in Zorp version 5 and earlier, the stack size was only 1 MB, and you could increase it by using the Thread stack limit option.

  • Automatically restart abnormally terminated instances: If enabled, Zorp automatically restarts instances that crash for some reasons.

  • Enable core dumps: If enabled, Zorp automatically creates core dumps when a Zorp instance crashes for some reasons. Core dumps are special log files and are needed for troubleshooting.

    For more details on core dumps see Section 10.11, Managing core dump files.