DMTCP 2.1 released

DMTCP version 2.1. has now been released.

As before, it runs on most Linux distros, and supports both x86 and x86_64
(Intel/AMD for 32- and 64-bits), and 32-bit ARM (ARMv7). In addition, the
older DMTCP version 1.2.x (currently 1.2.8) continues to be maintained, but on
a bug-fix basis only.

• Change needed for all plugins:
  • If you have plugins that include "dmtcpplugin.h", they will now have to be
    changed to include "dmtcp.h". This is to reflect that "dmtcp.h" has more
    uses than just for plugins.
• This new release includes:
  • some newly stable plugins - batch-queue, modify-env, ptrace (see below)
  • full support for 32-/64-bit multilib architecture. (see below)
  • other enhancements to the core feature set (see below)
  • adapting DMTCP to application requirements: removal of the old dmtcpaware
    interface in favor of the newer interface: test/plugin/applic-*ckpt/
    (see below)
  • attempt to restore current working directory on restart (may be impossible
    if restart host has different filesystem)
  • 'dmtcp_coordinator --port-file <FILE>' causes coordinator to write the port
  • number on which it listens into FILE. This is useful in
    conjunction with 'dmtcp_coordinator --port 0', which starts a coordinator
    at a random unused port.
  • 'dmtcp_restart --ckptdir \<DIR>' and 'dmtcp_restart_script.sh --ckptdir \<DIR>'
    will change to a new directory to hold checkpoint images on restart.
  • 'dmtcp_restart --no-strict-uid-checking'
    or 'dmtcp_coordinator --no-strict-uid-checking'
    [ allows a user with a different uid to restart a checkpoint image;
    process uid will be changed to that of the new user ]
  • './configure --enable-run-as-root' [ self explanatory; normally running
    as root is bad practice ]
  • a new internal plugin to handle 'ssh' uniformly; Some corner cases
    in checkpointing MPI could have been affected by this.
  • some bug fixes related to the new plugin software architecture initiated
    with DMTCP 2.0.
• Some newly stable plugins:
  This release continues to emphasize the use of DMTCP plugins.
  The plugins are now organized into two top-level subdirectories:
  • plugin - plugin is built by './configure; make', but must be invoked,
    typically through command-line option of 'dmtcp_launch'
  • contrib - plugin not built; user must cd to the subdirectory of the plugin,
    build it, and invoke it with 'dmtcp_launch --with-plugin ...'
  • Plugins in the top-level plugin directory:
    • ptrace : 'dmtcp_launch --ptrace'
      a plugin to support checkpointing ptrace-based applications,
      notably including GDB.
    • batch-queue : 'dmtcp_launch --batch-queue'
      a resource manager plugin that supports the Torque/PBS and SLURM
      batch queue systems. (This plugin is now mature, and was renamed
      from 'rm' in DMTCP-2.0 to 'batch-queue' to better reflect its use.)
      [ improved in DMTCP 2.1 ]
    • modify-env : 'dmtcp_launch --modify-env'
      Normally, on dmtcp_restart, a process can see only the original
      environment variables in effect during dmtcp_launch or set by the
      process itself. It is common to wish to update these environment
      variables based on the environment on the restart host
      (e.g., DISPLAY=$DISPLAY). This can be set in a file dmtcp_env.txt .
      [ new in DMTCP 2.1 ]
  • The contrib plugins include:
    • condor : support for HTCondor, a framework for high throughput computing
    • kvm : checkpointing of a KVM virtual machine
    • tun : support for tun networking (as in Tun/Tap) between a virtual
      machine and the host machine
    • python : support for checkpoint/restart within a Python session
    • infiniband : checkpointing over InfiniBand networks supports OFED
      InfiniBand API.
      (Note: If you are using a newer release of OFED, you may wish to use
      the rewrite of this plugin, to be available from the svn in late
      January, 2014.)
      [ improved in DMTCP 2.1 ]
    • ib2tcp : support for checkpointing computation over InfiniBand and
      restarting over TCP.
      [ new in DMTCP 2.1 ]
    • ckptfile : example/template for a plugin to change the default directory
      to receive checkpoint images. This can be important when restarting on
      a new host.
      [ new in DMTCP 2.1 ]
• Full support for 32-/64-bit multilib architecture:
  • The standard binary, dmtcp_launch, now supports both 32- and 64-bit programs.
    Further, a 64-bit program may invoke a 32-bit program and vice versa, as part
    of a single computation under DMTCP control.
• Other enhancements to the core feature set:
  • For extremely malloc-intensive programs, run-time overhead from several
    per cent to 20% has been observed. This is due to DMTCP deadlock
    avoidance. (The glibc implementation of malloc uses a global lock,
    that can result in deadlock if a user invokes malloc inside a plugin
    during checkpoint or restart.) If a user program is not using malloc
    in a plugin during checkpoint, then the user can disable this
    DMTCP deadlock avoidance scheme with a flag:
    dmtcp_launch --disable-alloc-plugin
    A future modification to DMTCP may remove this issue entirely.
• Adapting DMTCP to application requirements and to external environments:
  • The old 'dmtcpaware' API is being removed in favor of:
    test/plugin/applic-*ckpt/
    For details on this newer API, please read the QUICK-START file with this
    same heading: ADAPTING DMTCP TO ...