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March 27, 2017:
The 2.5 release is a minor one and introduces just one change. When the multi-process feature is used to limit the CPU usage of child processes, it can cause a fork bomb when a parent of LimitCPU is used as the target. The new 2.5 release attempts to avoid some situations where a fork bomb could happen.


November 24, 2016:
The new 2.4 release offers a new feature, the ability to monitor both a target process and that process's child processes. This feature throttles each new process forked from the target and applies the same rules to the new processes. The new feature is currently available only on Linux and can be activated using the "--monitor-forks" flag. The following example monitors Firefox and any processes Firefox might create:
cpulimit -l 25 --monitor-forks -- firefox



August 30, 2016:
A new release, version 2.3, introduces two new changes. First, the manual page has been updated to fix typos. Second, we have introduced a new command line parameter, --foreground (-f). The foreground flag indicates LimitCPU should remain running in the foreground while the target process is monitored. LimitCPU remains in the foreground, blocking, until the target process finishes. This may be useful in scripts where we want to launch and monitor a process and then quit when the target process is through. For example:
cpulimit -l 25 --foreground logrotate
In additional, there has been some code clean-up. This does not change performance at all, but it removes some old, unused code we did not need.


May 25, 2014:
By default, when LimitCPU exits, it sends any watched process the continue signal (SIGCONT). This insures the watched process keeps working after LimitCPU is terminated. It is now possible to send a specific signal to a watched process when LimitCPU is terminated. This means the user can specify whether the watched process continues to run, is terminated or paused. Signals can be specified using the -s or --signal command line parameter. See the README and manual pages for examples.


June 11, 2013:
We have released a minor update to the LimitCPU program. This version contains some minor code clean-up and introduces two new features.

Sometimes when a process gets out of control and gobbles up additional CPU cycles we don't merely want to throttle it, but actually terminate the process. LimitCPU now allows us to kill processes which go above their allotted CPU usage by using the "-k" command line flag.

The second feature compliments the terminate feature. Once a process has been killed using the -k flag it is possible to re-start the process fresh using the "-r" command line flag. For example, if we have a daemon which we know is likely to run into an infinite loop and we wish to terminate and then re-start the daemon we can use the command
cpulimit -l 10 -b -k -r my-daemon
The above command launches the my-daemon program and limits its CPU usage to 10%. Should the command use additional resources it is terminated and then my-daemon is run again.


September 15, 2012:
We are happy to report version 1.8 of LimitCPU is available for downloading. This release provides a few bug fixes and brings in patches from downstream projects. Changes include
  • LimitCPU should now successfully throttle mutli-thread processes running on multi-core machines when the desired CPU usage is over 100% (ie 150% or 200%).
  • LimitCPU should now compile on Mac OS X, though at this time the software has not been tested successfully on that platform.
  • Patch added from Gregor which should improve compiling on Debian.
  • Imported patch from FreeBSD. Users on FreeBSD should be able to compile LimitCPU by running "make freebsd" without requiring a patch.
  • Made verbose output easier to read for debugging purposes.
  • Imported test program, "busy", from the CPUlimit source tree. This program can be compiled by running "make tests".


June 6, 2012:
Version 1.7 of LimitCPU is now available. This new release introduces a number of new features, including
  • Programs can now be launched from LimitCPU's command line. For example the following will launch the Firefox web browser and limit it to using 25% of the CPU:
    cpulimit -l 25 firefox
  • We now try to detect how many CPUs are on the system and limit processes accordingly. If LimitCPU guesses incorrectly we can over-ride it using the -c flag.
  • Now LimitCPU only tries to adjust its scheduling priority once, and is more flexible as to which elevated priorities it will accept.
  • Version information has been added to the help screen.
  • LimitCPU will no longer make the mistake of trying to throttle its own process.
  • Minor code clean-up for readablity.


May 5, 2012:
Version 1.6 is now available. This release clears out some un-needed files, updates the copyright notice and should fix compiling LimitCPU on GNU/Hurd machines.


February 21, 2012:
Version 1.5 of LimitCPU is now available for download. This release updates the document and adds a new example for running LimitCPU from scripts. The Makefile has also been updated to use the default compiler on the system, with the option of falling back on GCC if no default is provided. The latest source code and updated README file can be found on our download page.


August 12, 2011:
We've made a few small changes to LimitCPU. Sanity checks have been put into place so we can handle situations where we cannot open entries in the proc file system. The CPU limit can now be higher than 100%, useful for multi-core machines. And a few checks have been put into the makefile to insure the program installs properly. The latest version, 1.4, can be found on our download page.


May 4, 2011:
LimitCPU 1.3 is now ready for download. This new release cleans up the documentation, clarifies the license and includes a copy of the Debian manual page. The new version can be found on our download page.


April 27, 2011:
I am happy to report the first release of LimitCPU, version 1.2, is now ready for download. This version is essentially CPUlimit 1.1, but with patches from Debian and Ubuntu applied. A changelog and README file have been added to the source tree, along with a formal license file and some improvements based on the port from FreeBSD. Please see our download page for a copy of the new release.