[Modules] load and unload true at the same time

[Martin S. <si...@sf...>]

Hi,

basically all of our modulefiles start with

set ld [module-info mode load]
set rm [module-info mode remove]

and then we do things depending on the values of $ld and $rm, e.g.,
loading/unloading of other prerequisite/conflicting modules. This never
worked correctly since it never occurred to us that
"module-info mode load" AND "module-info mode remove" could both be true
at the same time. Example:

===<module1>===
#%Module@VER@#

set ld [module-info mode load]
set rm [module-info mode remove]
module-verbosity "load: [module-info mode load] remove: [module-info mode remove] mode: [module-info mode]"

if { $ld } { module unload module2 }
if { $rm } { module load module2 }
===</module1>===

===<module2>===
#%Module@VER@#

set ld [module-info mode load]
set rm [module-info mode remove]
module-verbosity "load: [module-info mode load] remove: [module-info mode remove] mode: [module-info mode]"
===</module2>===

# module list
No Modulefiles Currently Loaded.
# module -v load module2
module2(5):VERB:4: load: 1 remove: 0 mode: load
# module -v load module1
module1(5):VERB:4: load: 1 remove: 0 mode: load
module2(5):VERB:4: load: 1 remove: 1 mode: load
# module list
Currently Loaded Modulefiles:
  1) module1
# module -v unload module1
module1(5):VERB:4: load: 0 remove: 1 mode: remove
module2(5):VERB:4: load: 1 remove: 1 mode: load
# module list
No Modulefiles Currently Loaded.

When module1 is loaded it "unloads" (I do not know what the code actually
does in this case) module2. In module2 then both [module-info mode load]
and [module-info mode remove] are 1, see the

module2(5):VERB:4: load: 1 remove: 1 mode: load

line. Obviously this has nonsensical consequences depending on what we
do within if { $ld } { ... } and if { $rm } { ... } blocks inside
module2.

The bug is in ModuleCmd_Load.c, line 129:

    if( load)
        g_flags |= M_LOAD;
    else
        g_flags |= M_REMOVE;

The flags are or'd, i.e., when a module is loaded when the M_REMOVE flag
is set in g_flags you end up with g_flags that have M_LOAD and M_REMOVE
set at the same time.
I am attaching a patch modules-3.2.8-load.patch that resolves the issue:

# module list
No Modulefiles Currently Loaded.
# module -v load module2
module2(5):VERB:4: load: 1 remove: 0 mode: load
# module -v load module1
module1(5):VERB:4: load: 1 remove: 0 mode: load
module2(5):VERB:4: load: 0 remove: 1 mode: remove
# module list
Currently Loaded Modulefiles:
  1) module1
# module -v unload module1
module1(5):VERB:4: load: 0 remove: 1 mode: remove
module2(5):VERB:4: load: 1 remove: 0 mode: load
# module list
Currently Loaded Modulefiles:
  1) module2

Since I am not familiar with the code I attach an alternative patch that
saves the flags before overwriting and restores them at the end.
I do not know why that should be necessary and believe that the simpler
patch should be ok.

Cheers,
Martin

-- 
Martin Siegert
Head, Research Computing
WestGrid/ComputeCanada Site Lead
IT Services                                phone: 778 782-4691
Simon Fraser University                    fax:   778 782-4242
Burnaby, British Columbia                  email: si...@sf...
Canada  V5A 1S6