gdb on a node

Wade Hampton wade.hampton at nsc1.net
Mon Nov 11 10:19:51 EST 2002


G'day,

I'm trying to debug a process on a remote node using Scyld
28CZ4.  For example, I was trying to get ganglia to work
on the cluster.

As PIDs appear on the head node, I figured that a gdb "attach"
would not work but it more or less did:

    bpsh 0 myprog

    ps eax | grep myprog

    get pid from that and then:

    bpsh 0 gdb my prog
    gdb> attach myprog's pid

This worked, but:

1)  It requires the program to be running first, possibly requiring changes
     to the program startup code.

2)  Typing ctrl-c following a gdb "continue" terminates the bpsh and the 
gdb,
     not pausing gdb as one would expect.


What I found that does not work, but based on my understanding,
should work:

    copy file to an NFS partition which the nodes have mounted:

        /data/xfer/myprog

    build the program with -ggdb to enable debugging....

    from the head node:

        cd /data/xfer/myprog
        bpsh 0 gdb myprog

    At this point, gdb should be running on the remote node with
    stdio forwarded to me.  It should be debugging my program.

        break main    -- or set any other breakpoint that should be hit
        run

    The program NEVER hits the beakpoint and runs to completion....

Any ideas?   Help would be most appreciated.

Cheers,
--
Wade Hampton

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