resource.h broken (not implemented yet?)

[scottmc]

May be related to ticket #2817 perhaps not, python's test_resource.py passes the first test, then fails the next 3 and then crashes on getrusage.

~/develop/python/Lib/test> python test_resource.py
test_args (__main__.ResourceTest) ... ok
test_fsize_enforced (__main__.ResourceTest) ... ERROR
test_fsize_ismax (__main__.ResourceTest) ... ERROR
test_fsize_toobig (__main__.ResourceTest) ... ERROR
test_getrusage (__main__.ResourceTest) ... Kill Thread
~/develop/python/Lib/test> 

[Timothy_Gu]

The first three errors are easily reproducible with

#include <errno.h>
#include <stdio.h>
#include <sys/resource.h>

int
main()
{
    struct rlimit rl = {0};
    int ret;
    ret = get_rlimit(RLIMIT_FSIZE, &rl);
    printf("%d %d %" __HAIKU_PRI_PREFIX_ADDR "d %" __HAIKU_PRI_PREFIX_ADDR "d\n", ret, errno, rl.rlim_cur, rl.rlim_max);
    return ret;
}

[Timothy_Gu]

Apparently only part of POSIX spec for [gs]et_rlimit is implemented, and when it encounters an unimplemented property it just returns EINVAL.

See ​https://github.com/haiku/haiku/blob/449f7f5a7b9d381c1eeab3ddfbdba0db0ce05c22/src/system/kernel/thread.cpp#L1310-L1327

I'm not sure what the right thing to do is here. Should I make it return ENOSYS instead? But that would break a lot of apps relying on POSIX. Or I could make it return 0 as the values.

List of unimplemented properties:

• RLIMIT_CPU: maximum amount of CPU time, in seconds, used by a process
• RLIMIT_DATA: maximum size of a process' data segment, in bytes
• RLIMIT_FSIZE: maximum size of a file, in bytes, that may be created by a process
• RLIMIT_STACK (implemented in get_rlimit() but not in set): maximum size of the initial thread's stack, in bytes
• RLIMIT_AS: maximum size of a process' total available memory, in bytes

I will investigate the getrusage() failure soon.

[Timothy_Gu]

The getrusage() function itself works fairly well, from my standalone test program. I believe the issue is in one of the patches applied to get python to build, as the segfault seems to be from the python internals. I will try to confirm.

[Timothy_Gu]

Interestingly, the getrusage() issue only seems to be reproducible on x86_gcc2. x86_64 does not have this issue. I will test pure x86 soon.

[Timothy_Gu]

My program used to test getrusage():

#include <errno.h>
#include <stdio.h>
#include <sys/resource.h>

// From https://github.com/python/cpython/blob/2.7/Modules/resource.c#L20
#define doubletime(TV) ((double)(TV).tv_sec + (TV).tv_usec * 0.000001)

int
main()
{
    struct rusage ru = {0};
    int ret;
    ret = getrusage(RUSAGE_SELF, &ru);
    printf("%d %d %f %f\n", ret, errno, doubletime(ru.ru_utime), doubletime(ru.ru_stime));
    return ret;
}

It prints something like this:

0 0 0.1034 0.1620

The first two 0's indicate that there is no error (ret and errno resp.).

[Timothy_Gu]

Unfortunately no, getrusage() doesn't work on x86_gcc4 either.

[Timothy_Gu]

Hah found where the issue is. It is in a patch in Python. Will submit a PR to haikuports soon.

[pulkomandy]

Please include a link to your PR so we can check and close this. Thanks for investigating!

[Timothy_Gu]

Replying to pulkomandy:

Please include a link to your PR so we can check and close this. Thanks for investigating!

Here: ​https://bitbucket.org/haikuports/haikuports/pull-request/453/fix-python-resource-module/diff

[pulkomandy]

Ok, PR is merged. It would still be nice to actually implement things so we don't have to hack around it in Python sources, but at least the crash is fixed now.