Hi again Jaijun,

I've gone ahead and downloaded and tested the latest 2.4 release of
DMTCP (version 2.4.8) and it appears that this --no-coordinator bug
has not yet been fixed.  I am getting a return value of zero from
from the dmtcp_checkpoint() function after returning from a
checkpoint (instead of the expected DMTCP_AFTER_CHECKPOINT).

For this reason, DMTCP version 2.4 is not an option for us as we
require our program to be run without any coordinator.

If anyone could respond with some information on getting DMTCP
version 2.3.1 to pause correctly upon restart using the
environment variable MTCP_RESTART_PAUSE mentioned in the
documentation, it would be greatly appreciated.  As stated at
the start of this thread, I've not been able to get my restarted
processes to pause using this environment variable prior to the
dmtcp_launch command as stated in the documentation.

Thank you,
Rick


-----------------------------------------------------------------------

On Tue, 8 Aug 2017, Jiajun Cao wrote:

Hi Rick,

The support for allowing gdb attach on restart was not added until
the 2.4 release.

Is there any possibility that you upgrade the installation to a
newer version? Note you don't need to have root privilege to do
that. If you want to test it locally, just compile the source code,
and add the bin path to your $PATH env var.

Best,
Jiajun

On Tue, Aug 08, 2017 at 03:53:02PM -0400, dmtcp-fo...@gusbus.org wrote:

Hi there,

I'm trying to understand the documented options for debugging a
restarted DMTCP process.

I've been testing a few different environment variables trying to
get the dmtcp_restart process to pause for 15 seconds like it is
suppose to, so that I can attach to it with gdb.

There are various options in the documentation, environment variables
like:

DMTCP_RESTART_PAUSE
DMTCP_RESTART_PAUSE2
DMTCP_GDB_ATTACH_ON_RESTART

I am currently locked into using DMTCP version 2.3.1 at the present
time.  My program was compiled using gcc 6.4.0.  I am running under
CentOS release 6.8 Final, kernal 2.6.32-642.4.2.el6.x86_64 #1 SMP.


Have noted that the documentation states that prior to version 2.4
of DMTCP, the environment variable to use is named MTCP_RESTART_PAUSE.

I have tried setting MTCP_RESTART_PAUSE prior to the dmtcp_launch
command, and prior to both dmtcp_launch and dmtcp_restart commands
with no luck.  I am able to use gdb to attach to the process (more
easily from a separate terminal because of the standard output being
produced from my process in the dmtcp_restart process terminal) but
since there is no pause, gdb doesn't attach until later in the process
after the restart, all based on how quickly I can get the gdb attach
commmand typed in and entered.  Not really a reliable way to go :)

In any event, if there are known issues with regard to getting the
restart process to pause in version DMTCP 2.3.1, then that would
explain it, if however I am doing something wrong, then any help
would be appreciated.

My normal series of run commands go like this (just like the DMTCP
documentation)

MTCP_RESTART_PAUSE=1 dmtcp_launch --disable-alloc-plugin --no-coordinator --port 0 
program.exe < input.dat

dmtcp_restart --port 0 --port-file dmtcpportfile checkpoint.dmtcp < input.int &

Do you think any of the command line options are causing any issues, like
my lack of using the coordinator?  Also, my program always reads a file from
standard input even during a restart.

Thanks,
Rick



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