This section provides information specific to the Linux port of HTCondor. Linux is a difficult platform to support. It changes frequently, and HTCondor has some extremely system-dependent code, such as the checkpointing library.
HTCondor is sensitive to changes in the following elements of the system:
The kernel version
The version of the GNU C library (glibc)
the version of GNU C Compiler (GCC) used to build and link HTCondor jobs. This matters for HTCondor’s standard universe, which provides checkpoints and remote system calls.
The HTCondor Team tries to provide support for various releases of the distribution of Linux. Red Hat is probably the most popular Linux distribution, and it provides a common set of versions for the above system components at which HTCondor can aim support. HTCondor will often work with Linux distributions other than Red Hat (for example, Debian or SuSE) that have the same versions of the above components. However, we do not usually test HTCondor on other Linux distributions and we do not provide any guarantees about this.
New releases of Red Hat usually change the versions of some or all of the above system-level components. A version of HTCondor that works with one release of Red Hat might not work with newer releases. The following sections describe the details of HTCondor’s support for the currently available versions of Red Hat Linux on x86 architecture machines.
Linux Address Space Randomization¶
Modern versions of Red Hat and Fedora do address space randomization, which randomizes the memory layout of a process to reduce the possibility of security exploits. This makes it impossible for standard universe jobs to resume execution using a checkpoint. When starting or resuming a standard universe job, HTCondor disables the randomization.
To run a binary compiled with condor_compile in standalone mode, either initially or in resumption mode, manually disable the address space randomization by modifying the command line. For a 32-bit architecture, assuming an HTCondor-linked binary called myapp, invoke the standalone executable with:
$ setarch i386 -L -R ./myapp
For a 64-bit architecture, the resumption command will be:
$ setarch x86_64 -L -R ./myapp
Some applications will also need the -B option.
The command to resume execution using the checkpoint must also disable address space randomization, as the 32-bit architecture example:
$ setarch i386 -L -R myapp -_condor_restart myapp.ckpt