Horton

Re: refactoring basebackup.c

Dmitry Dolgov <9erthalion6@gmail.com>

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From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jeevan Ladhe <jeevan.ladhe@enterprisedb.com>, Mark Dilger <mark.dilger@enterprisedb.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, tushar <tushar.ahuja@enterprisedb.com>
Date: 2021-11-15T16:26:41Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Document BaseBackupSync and BaseBackupWrite wait events.

  2. Support long distance matching for zstd compression

  3. Fix possible NULL-pointer-deference in backup_compression.c.

  4. Allow parallel zstd compression when taking a base backup.

  5. Make PostgreSQL::Test::Cluster::run_log() return a useful value.

  6. Fix a few goofs in new backup compression code.

  7. Replace BASE_BACKUP COMPRESSION_LEVEL option with COMPRESSION_DETAIL.

  8. Add 'basebackup_to_shell' contrib module.

  9. Allow extensions to add new backup targets.

  10. Change HAVE_LIBLZ4 and HAVE_LIBZSTD tests to USE_LZ4 and USE_ZSTD.

  11. pg_basebackup: Clean up some bogus file extension tests.

  12. pg_basebackup: Avoid unclean failure with server-compression and -D -.

  13. Fix LZ4 tests for remaining buffer space.

  14. Add support for zstd base backup compression.

  15. pg_basebackup: Allow client-side LZ4 (de)compression.

  16. Add suport for server-side LZ4 base backup compression.

  17. Add min() and max() aggregates for xid8.

  18. Remove superfluous variable.

  19. pg_basebackup: Cleaner handling when compression is multiply specified.

  20. Allow server-side compression to be used with -Fp.

  21. pg_basebackup: Fix a couple of recently-introduced bugs.

  22. Tidy up a few cosmetic issues related to pg_basebackup.

  23. Server-side gzip compression.

  24. Unbreak pg_basebackup/t/010_pg_basebackup.pl on msys

  25. Suppress variable-set-but-not-used warning from clang 13.

  26. Extend the options of pg_basebackup to control compression

  27. Support base backup targets.

  28. Modify pg_basebackup to use a new COPY subprotocol for base backups.

  29. Document that tar archives are now properly terminated.

  30. Fix thinko in bbsink_throttle_manifest_contents.

  31. Have the server properly terminate tar archives.

  32. Minimal fix for unterminated tar archive problem.

  33. Introduce 'bbstreamer' abstraction to modularize pg_basebackup.

  34. Introduce 'bbsink' abstraction to modularize base backup code.

  35. Refactor basebackup.c's _tarWriteDir() function.

  36. Flexible options for CREATE_REPLICATION_SLOT.

  37. Flexible options for BASE_BACKUP.

> On Fri, Nov 05, 2021 at 11:50:01AM -0400, Robert Haas wrote:
> On Tue, Nov 2, 2021 at 10:32 AM Robert Haas <robertmhaas@gmail.com> wrote:
> > Meanwhile, I think it's probably OK for me to go ahead and commit
> > 0001-0003 from my patches at this point, since it seems we have pretty
> > good evidence that the abstraction basically works, and there doesn't
> > seem to be any value in holding off and maybe having to do a bunch
> > more rebasing.
>
> I went ahead and committed 0001 and 0002, but got nervous about
> proceeding with 0003.

Hi,

I'm observing a strange issue which I can only relate to bef47ff85d
where bbsink abstraction was introduced. The problem is about failing
assertion when doing:

    DETAIL:  Failed process was running: BASE_BACKUP ( LABEL 'pg_basebackup base backup',  PROGRESS,  WAIT 0,  MAX_RATE 102400,  MANIFEST 'yes')

Walsender tries to send a backup manifest, but crashes on the trottling sink:

    #2  0x0000560857b551af in ExceptionalCondition (conditionName=0x560857d15d27 "sink->bbs_next != NULL", errorType=0x560857d15c23 "FailedAssertion", fileName=0x560857d15d15 "basebackup_sink.c", lineNumber=91) at assert.c:69
    #3  0x0000560857918a94 in bbsink_forward_manifest_contents (sink=0x5608593f73f8, len=32768) at basebackup_sink.c:91
    #4  0x0000560857918d68 in bbsink_throttle_manifest_contents (sink=0x5608593f7450, len=32768) at basebackup_throttle.c:125
    #5  0x00005608579186d0 in bbsink_manifest_contents (sink=0x5608593f7450, len=32768) at ../../../src/include/replication/basebackup_sink.h:240
    #6  0x0000560857918b1b in bbsink_forward_manifest_contents (sink=0x5608593f74e8, len=32768) at basebackup_sink.c:94
    #7  0x0000560857911edc in bbsink_manifest_contents (sink=0x5608593f74e8, len=32768) at ../../../src/include/replication/basebackup_sink.h:240
    #8  0x00005608579129f6 in SendBackupManifest (manifest=0x7ffdaea9d120, sink=0x5608593f74e8) at backup_manifest.c:373

Looking at the similar bbsink_throttle_archive_contents it's not clear
why comments for both functions (archive and manifest throttling) say
"pass archive contents to next sink", but only bbsink_throttle_manifest_contents
does pass bbs_next into the bbsink_forward_manifest_contents. Is it
supposed to be like that? Passing the same sink object instead the next
one into bbsink_forward_manifest_contents seems to solve the problem in
this case.