Newsgroups: comp.parallel.pvm
From: tomrz@avarice.ugcs.caltech.edu (Tom Zavisca)
Subject: pvm and the AT&T task library
Summary: funky malloc problems
Keywords: AT&T malloc pvm_spawn
Organization: California Institute of Technology, Pasadena
Date: 11 Dec 1994 10:17:19 GMT
Message-ID: <3cejjf$c4s@gap.cco.caltech.edu>
                        
To the benevolent pvm experts,

	I am writing a C++ application built on top of both pvm and
the AT&T task library.  At one point everything was working(process
spawning and communication), but then I changed a few things ..., and
now I get a segmentation fault within a call to pvm_spawn().  MY buest
guess is that before, pvm_spawn was only called from within the main
task, while in the later version of my code, pvm_spawn() is called
from within a subsidiary task(thread).  I would be very grateful for
any information on how to approach this problem or who to contact for
assistance.  Attached below is a gdb backtrace of the problem.

Thankyou
-Tom Zavisca
tomrz@ugcs.caltech.edu

<------- the last output when run under gdb ---->

MPMT Comment: Group::SpawnGroup() pvm_spawn("RingCommTest",(char **)0,PvmTaskDefault,"stun4p",1,pidTable(7ce88)+0)) about to be called

Program received signal 11, Segmentation fault
0xf770474c in malloc ()

<---- The back trace  ---->

#0  0xf770474c in malloc ()
#1  0x45920 in da_new (len=4096) at ../pvmdabuf.c:58
#2  0x44f4c in fr_new (len=4096) at ../pvmfrag.c:81
#3  0x41a34 in pvm_mkbuf (enc=1) at ../lpvmpack.c:1676
#4  0x3e810 in pvm_spawn (file=0x7f1e0 "RingCommTest", argv=0x7eb88, flags=0, 
    where=0x7f208 "stun4p", count=1, tids=0x7ce88) at ../lpvmgen.c:963
#5  0x1eff4 in SpawnGroup__5GroupSFP5GroupP11ProcessInfo (g::g()=<unknown struct>,
     __1pInfo=<unknown struct>) at Pid.C:299
#6  0x1867c in MPMT_Main (__1input=0x0) at MPMT_Starter.C:22
#7  0x37394 in __ct__11MPMT_ThreadFiPc13MPMT_StackTagT1PFPc_vT2 (__0this=0x7d040, 
    __1type=<unknown struct>, __1name=0x6ce24, __1stackType=SHARED, 
    __1stackSize=<unknown struct>, __1Compute=<unknown struct>, __1args=0x0)
    at MPMT_Thread.C:28
#8  0x2b88c in Compute__12MPMT_ProcessSFv () at MPMT_Process.C:144
#9  0x2b548 in DoTheComputation__12MPMT_ProcessSFv () at MPMT_Process.C:37
#10 0x2ba44 in main () at MPMT_Process.C:187




