[Bug default/30274] New: RFE have fedabipkgdiff prefer debuginfod when available

[Bug default/30274] New: RFE have fedabipkgdiff prefer debuginfod when available

[woodard at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30274

            Bug ID: 30274
           Summary: RFE have fedabipkgdiff prefer debuginfod when
                    available
           Product: libabigail
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: default
          Assignee: dodji at redhat dot com
          Reporter: woodard at redhat dot com
                CC: libabigail at sourceware dot org
  Target Milestone: ---

This came up as a continuation of PR#29911 one thing that FchE noticed was that
fedabipkgdiff was downloading debuginfo packages rather than fetching the data
from debuginfod even though libabigail being based on elfutils has the
capability to fetch debuginfod. 

What we figured out was that somewhere in fedabipkgdiff it was deciding to and
fetching the debuginfod from koji and then it would prefer that over debuginfod
data. It was FchE that noticed this but once I started thinking about it, I
realized that this could greatly improve fedabipkgdiff. As I was running my
full distro test this is the kind of thing that I noticed in my top session as
I monitored progress. Note how many processes are running the cpio to unpack a
package vs how many jobs actually running abipkgdiff.

top - 18:30:34 up 1 day,  9:34,  4 users,  load average: 31.53, 37.87, 42.06
Tasks: 581 total,  16 running, 565 sleeping,   0 stopped,   0 zombie
%Cpu(s): 39.6 us, 12.4 sy,  0.0 ni, 23.8 id, 24.0 wa,  0.1 hi,  0.1 si,  0.0 st
MiB Mem : 128119.5 total,  65441.2 free,   5400.2 used,  58509.8 buff/cache
MiB Swap:  32124.0 total,  31700.5 free,    423.5 used. 122719.3 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND  
3199639 ben       20   0 1635092   1.3g 131052 S  99.7   1.1   0:18.00
abipkgdiff                                                                      
3199358 ben       20   0  722808 596612  47728 S  99.3   0.5   0:08.26
abipkgdiff                                                                      
3183615 ben       20   0  189168  91344  12564 S  99.7   0.1   4:30.37
abipkgdiff                                                                      
3087305 ben       20   0  268540  42156  15720 R  99.7   0.0  28:23.80 python   
3155605 ben       20   0  266940  40540  15676 R 100.0   0.0   9:20.09 python   
3199415 ben       20   0  266036  39764  15728 R 100.0   0.0   0:22.19 python   
3195139 ben       20   0  265384  39100  15732 R 100.0   0.0   1:41.93 python   
3197990 ben       20   0  265384  39084  15716 R 100.0   0.0   0:48.76 python   
3156907 ben       20   0  265384  39076  15740 R  99.7   0.0  10:42.88 python   
3199255 ben       20   0  265388  38964  15788 R  99.7   0.0   0:30.69 python   
3172092 ben       20   0  265388  38896  15712 R 100.0   0.0   7:19.67 python   
3185309 ben       20   0  265388  38868  15712 R  99.7   0.0   4:01.49 python   
3188347 ben       20   0  264996  38720  15792 R  99.7   0.0   3:21.35 python   
3196118 ben       20   0  265132  38656  15696 R 100.0   0.0   1:21.71 python   
3081909 ben       20   0  264996  38616  15712 R  94.7   0.0  24:21.68 python   
3199647 ben       20   0  264996  38584  15724 S  99.7   0.0   0:18.55 python   
3200028 ben       20   0   20860  14364   4752 D   0.7   0.0   0:00.04 rpm2cpio 
3200000 ben       20   0   20868  14328   4716 D   1.3   0.0   0:00.07 rpm2cpio 
3199717 ben       20   0   20784  14260   4492 D   2.7   0.0   0:00.25 rpm2cpio 
3191525 ben       20   0   20784  14216   4712 D   1.0   0.0   0:00.92 rpm2cpio 
3199737 ben       20   0   20860  14212   4600 D   0.7   0.0   0:00.07 rpm2cpio 
3189094 ben       20   0   20860  14168   4552 D   1.3   0.0   0:02.47 rpm2cpio 
3199830 ben       20   0   20824  14148   4536 D   2.3   0.0   0:00.19 rpm2cpio 
3200088 ben       20   0   20860  14104   4488 R  16.9   0.0   0:00.51 rpm2cpio 
3199794 ben       20   0   20860  14064   4716 D   0.7   0.0   0:00.10 rpm2cpio 
3192390 ben       20   0   20860  14008   4460 D   0.3   0.0   0:00.92 rpm2cpio 
3199496 ben       20   0   20856  14004   4552 D   0.3   0.0   0:00.10 rpm2cpio 
3192391 ben       20   0  221068   1172   1080 S   0.3   0.0   0:01.02 cpio     
3191526 ben       20   0  221068   1168   1076 S   1.0   0.0   0:00.84 cpio     
3199718 ben       20   0  221068   1160   1068 S   3.0   0.0   0:00.31 cpio     
3189095 ben       20   0  221068   1156   1064 S   1.3   0.0   0:02.02 cpio     
3200029 ben       20   0  221068   1156   1064 S   1.0   0.0   0:00.04 cpio     
3199497 ben       20   0  221068   1136   1044 S   0.3   0.0   0:00.07 cpio     
3199831 ben       20   0  221068   1132   1040 S   2.7   0.0   0:00.21 cpio     
3200089 ben       20   0  221068   1132   1040 R  18.3   0.0   0:00.55 cpio     
3199795 ben       20   0  221068   1108   1012 S   0.3   0.0   0:00.09 cpio     
3200001 ben       20   0  221068   1108   1012 S   1.7   0.0   0:00.09 cpio     
  20964 root      20   0       0      0      0 S   0.3   0.0   0:47.66 NFSv4
callback                                                                        
2612147 root      20   0       0      0      0 I   0.3   0.0   0:00.51
kworker/9:2-events_freezable                                                    
2858412 root      20   0       0      0      0 I   0.3   0.0   0:05.50
kworker/u256:6-events_unbound                                                   
2953630 root      20   0       0      0      0 I   0.3   0.0   0:04.37
kworker/u256:0-rpciod                                                           
3096956 root      20   0       0      0      0 I   0.3   0.0   0:01.41
kworker/u256:5-events_unbound                                                   
3182633 root      20   0       0      0      0 I   0.3   0.0   0:00.34
kworker/u256:9-rpciod 

Furthermore fedabipkgdiff creates a cache directory of rpms. I have frequently
had test terminate because I've run out of space in this directory. A notable
percentage of the files that end up in the cache directory are the debuginfo
packages.

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[Bug default/30274] RFE have fedabipkgdiff prefer debuginfod when available

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30274

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> ---
fedabipkgdiff does a busy loop on waitpid() on the abipkgdiff child process:

@log_call
def abipkgdiff(cmp_half1, cmp_half2):
    [...]
    proc = subprocess.Popen(' '.join(cmd), shell=True,
                            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                            universal_newlines=True)
    # So we could have done: stdout, stderr = proc.communicate()
    # But then the documentatin of proc.communicate says:
    #
    #    Note: The data read is buffered in memory, so do not use this
    #    method if the data size is large or unlimited. "
    #
    # In practice, we are seeing random cases where this
    # proc.communicate() function does *NOT* terminate and seems to be
    # in a deadlock state.  So we are avoiding it altogether.  We are
    # then busy looping, waiting for the spawn process to finish, and
    # then we get its output.
    #

    while True:
        if proc.poll() != None:
            break


Not sure that interpretation of python docs is correct, but even then, a wee
bit of sleep wouldn't hurt.

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[Bug default/30274] RFE have fedabipkgdiff prefer debuginfod when available

[woodard at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30274

--- Comment #2 from Ben Woodard <woodard at redhat dot com> ---
One thing that I can say from experience is when there are a lot of
differences, the size of output files is a few hundred thousand lines and
probably amounts to a couple of megabytes of text. This is tiny in relation to
the size of memory used by abipkgdiff itself when building the corpus. (I've
seen up to 25G just casually watching top.) So to me it sounds like the concern
that led to that design decision is unwarranted.

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