Re: backup manifests and contemporaneous buildfarm failures

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, David Steele <david@pgmasters.net>, Andres Freund <andres@anarazel.de>, Noah Misch <noah@leadboat.com>, Stephen Frost <sfrost@snowman.net>, Amit Kapila <amit.kapila16@gmail.com>, Suraj Kharage <suraj.kharage@enterprisedb.com>, tushar <tushar.ahuja@enterprisedb.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, Rushabh Lathia <rushabh.lathia@gmail.com>, Tels <nospam-pg-abuse@bloodgate.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Jeevan Chalke <jeevan.chalke@enterprisedb.com>, vignesh C <vignesh21@gmail.com>
Date: 2020-04-03T22:48:01Z
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. Try to avoid compiler warnings in optimized builds.

  2. Fix option related issues in pg_verifybackup.

  3. Add index term for backup manifest in documentation.

  4. Code review for backup manifest.

  5. Document the backup manifest file format.

  6. Fix typo in pg_validatebackup documentation.

  7. Exclude backup_manifest file that existed in database, from BASE_BACKUP.

  8. Msys2 tweaks for pg_validatebackup corruption test

  9. Fix resource management bug with replication=database.

  10. Be more careful about time_t vs. pg_time_t in basebackup.c.

  11. pg_validatebackup: Fix 'make clean' to remove tmp_check.

  12. pg_validatebackup: Also use perl2host in TAP tests.

  13. Generate backup manifests for base backups, and validate them.

  14. Add checksum helper functions.

  15. pg_waldump: Add a --quiet option.

  16. Catversion bump for b9b408c48724

  17. pg_basebackup: Refactor code for reading COPY and tar data.

  18. Use a ResourceOwner to track buffer pins in all cases.

  19. Use ARMv8 CRC instructions where available.

  20. Logical replication support for initial data copy

  21. Use Intel SSE 4.2 CRC instructions where available.

  22. Switch to CRC-32C in WAL and other places.

  23. Remove support for 64-bit CRC.

  24. Change CRCs in WAL records from 64bit to 32bit for performance reasons.

Thomas Munro <thomas.munro@gmail.com> writes:
> Same here, on elver.  I see pg_subtrans has been chmod(0)'d,
> presumably by the perl subroutine mutilate_open_directory_fails.  I
> see this in my inbox (the build farm wrote it to stderr or stdout
> rather than the log file):

> cannot chdir to child for
> pgsql.build/src/bin/pg_validatebackup/tmp_check/t_003_corruption_master_data/backup/open_directory_fails/pg_subtrans:
> Permission denied at ./run_build.pl line 1013.
> cannot remove directory for
> pgsql.build/src/bin/pg_validatebackup/tmp_check/t_003_corruption_master_data/backup/open_directory_fails:
> Directory not empty at ./run_build.pl line 1013.

I'm guessing that we're looking at a platform-specific difference in
whether "rm -rf" fails outright on an unreadable subdirectory, or
just tries to carry on by unlinking it anyway.

A partial fix would be to have the test script put back normal
permissions on that directory before it exits ... but any failure
partway through the script would leave a time bomb requiring manual
cleanup.

On the whole, I'd argue that testing that behavior is not valuable
enough to take risks of periodically breaking buildfarm members
in a way that will require manual recovery --- to say nothing of
annoying developers who trip over it.  So my vote is to remove
that part of the test and be satisfied with checking the behavior
for an unreadable file.

This doesn't directly explain the failure-at-next-configure behavior
that we're seeing in the buildfarm, but it wouldn't be too surprising
if it ends up being that the buildfarm client script doesn't manage
to fully recover from the situation.

			regards, tom lane