Hi John --

Seeing this stack trace is very helpful (and saves me time I don't have to reproduce locally), thanks!

Would you try this once more adding the --no-inline flag to your list of 'chpl' compiler options? I'm curious whether that'll give us additional information in the stack trace about some routines that may have been inlined in the previous version.

Thanks,
-Brad


On Mon, 16 Mar 2015, John MacFrenz wrote:

Hi,

this was the problem, now I managed to get the backtrace. Unfortunately I 
really can't make much sense of it... I'm rather surprised that the error 
happens in constructor of the class (EvenPolicy), but commenting out a 
seemingly unrelated forall loop makes the program work... Anyway, here's the 
stack


#0  gdbShouldBreakHere () at gdb.c:27
#1  0x0000000000618063 in chpl_exit_common (status=1, all=0) at chplexit.c:38
#2  0x00000000006180d1 in chpl_exit_any (status=1) at chplexit.c:57
#3  0x0000000000611d7a in chpl_error (
   message=0x6d713d "attempt to dereference nil", lineno=165,
   filename=0x6d77f0 
"/home/john/projects/chapel/chapel/modules/internal/ChapelArray.chpl") at 
error.c:85
#4  0x00000000004c085d in chpl_check_nil (
   filename=0x6d77f0 
"/home/john/projects/chapel/chapel/modules/internal/ChapelArray.chpl", 
lineno=165, ptr=0x0)
   at 
/home/john/projects/chapel/chapel/runtime//include/chpl-comm-compiler-macros.h:196
#5  chpl__convertRuntimeTypeToValue2 (d=0x7fffffffa4b0, _retArg=0x7fffffffa4a0)
   at ChapelArray.chpl:165
#6  0x00000000005c0547 in EvenPolicy_chpl (dom_chpl=0x91bc00 <Space_chpl>,
   targetLocales_chpl=0x7fffffffcbb0) at VariBlockPolicies.chpl:334
#7  0x0000000000518652 in chpl__init_test2 (_ln_chpl=1,
   _fn_chpl=0x6d7dbb "src/test2.chpl") at test2.chpl:25
#8  0x000000000051f9bf in chpl_gen_main (_arg=0x928330 <chpl_gen_main_arg>)
   at test2.chpl:1
#9  0x0000000000617fe8 in chpl_executable_init () at chpl-init.c:269
#10 0x000000000061cdeb in chpl_task_callMain (
   chpl_main=0x617fcb <chpl_executable_init>) at tasks-fifo.c:394
---Type <return> to continue, or q <return> to quit---
#11 0x000000000060e784 in main (argc=6, argv=0x7fffffffd948) at main.c:32


The line 334 in VariBlockPolicies.chpl is

proc EvenPolicy(dom: domain, targetLocales: [] locale = Locales, param rank = 
dom.rank, type idxType = dom.idxType) {


17.03.2015, 00:37, "Brad Chamberlain" <[email protected]>:
I thought --gdb should set this breakpoint automatically, but must be
mis-remembering...  Would you try typing:

         break gdbShouldBreakHere

in each of the gdb consoles before typing 'run' and see if that helps?

Thanks, and sorry for my bad memory if this works,
-Brad

On Mon, 16 Mar 2015, John MacFrenz wrote:
 Hi,

 I had already tried that, and tried again after your post, but
 unfortunately couldn't get it work. I can get the program run in gdb and
 crash, but when trying to see the backtrace gdb just says "no stack" on
 both locales.

 17.03.2015, 00:13, "Brad Chamberlain" <[email protected]>:
 Hi John --

 Since everyone here is sprinting toward the code freeze for 1.11, I'll
 send out a pointer rather than diving into an analysis at present:

 Have you discovered the CHPL_COMM_USE_GDB environment variable described
 in doc/[release/]README.executing?  With it and GASNet, you can run your
 program, popping up an xterm per locale which tends to work for failures
 that fail on a small number of nodes (< 4 or so).  Compiling with -g and
 --cpp-lines and running with the --gdb flag should cause the program to
 break when this error is printed out, permitting you to get the stack
 trace that led to the error, which may help.

 If you get a stack trace but still can't determine why the error is
 occurring, feel free to send it along.

 -Brad

 On Mon, 16 Mar 2015, John MacFrenz wrote:
  Hi,

  I'm having a problem where my program fails with error:
  /home/john/projects/chapel/chapel/modules/internal/ChapelArray.chpl:165: 
error: attempt to dereference nil

  I haven't had success in trying to isolate the problem so unfortunately I 
don't have a simple example file which would reproduce the problem. However I 
have a test in my git branch of chapel which causes the problem. The branch in 
question is here
  https://github.com/jfrenz/chapel/tree/VariBlockDist
  The failing test is located at 
test/distributions/jfrenz/block-variblock/simple-coexist.chpl . If you comment 
out either of the forall loops in that file it runs fine. I have had it fail at 
least with GASNET_SPAWNFN=L and two or four locales.

  In that git branch I have modified only files in modules/dists , 
modules/standard and in test .

  Chpl info:

  CHPL_HOST_PLATFORM: linux64
  CHPL_HOST_COMPILER: gnu
  CHPL_TARGET_PLATFORM: linux64
  CHPL_TARGET_COMPILER: gnu
  CHPL_TARGET_ARCH: unknown
  CHPL_LOCALE_MODEL: flat
  CHPL_COMM: gasnet
   CHPL_COMM_SUBSTRATE: udp
   CHPL_GASNET_SEGMENT: everything
  CHPL_TASKS: fifo
  CHPL_LAUNCHER: amudprun
  CHPL_TIMERS: generic
  CHPL_MEM: cstdlib
  CHPL_MAKE: make
  CHPL_ATOMICS: intrinsics
   CHPL_NETWORK_ATOMICS: none
  CHPL_GMP: gmp
  CHPL_HWLOC: none
  CHPL_REGEXP: re2
  CHPL_WIDE_POINTERS: struct
  CHPL_LLVM: none
  CHPL_AUX_FILESYS: none

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