Difference between revisions of "Criu-coredump"

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Revision as of 16:54, 8 May 2015

Generate valid core dump from CRIU images.

Description

CRIU images contain lots of information about process state. In fact, it is sufficient enough to generate a valid core dump which can be later be used by gdb, for example. criu-coredump does exactly that, it takes a directory with CRIU images and produces Elf core dumps.

Basically, you can use CRIU to checkpoint task when you need it (i.e. when it hangs, or when an error occures) or make your application call CRIU via one of its interfaces(CLI, RPC or C library) and then produce core dump and inspect it via gdb.

To generate core dump of your application you don't even need to be a root, it is enough for you to be the owner of that task. For that all you have two choices: 1) Use CRIU service running and use RPC or C_API. It is useful if you want your app to automatically call CRIU. 2) Use CRIU binary with suid bit set.

criu-coredump project provides both cmdline tool and python module(criu_coredump), so you can use it in your python apps.

Limitations

For now only x86_64 is supported. The matter of supporting other architectures supported by CRIU is to use proper constants in elf header and provide proper arch-dependent notes.

Some notes in coredump are not fullfilled(i.e. SIGINFO).

VVAR and VSYSCALL vmas are just filled with zeroes, as CRIU doesn't currently provide them. VVAR is a tricky one and gdb also has problems dumping it[1]. VSYSCALL in theory could just be read from current process, so it should be quite easy to fix.

Installation

$ python setup.py install

Usage

criu-coredump [-h] [-i IN] [-p PID] [-o OUT]

optional arguments:
  -h, --help         show this help message and exit
  -i IN, --in IN     directory where to get images from.
  -p PID, --pid PID  generate core dump of a process identified by PID.
                     If not specified -- generating for each pid.
  -o OUT, --out OUT  directory to write core dump to.

Project resources

Project is located at GitHub.