[MDEV-29764] mariabackup hangs forever if using parallel threads Created: 2022-10-11  Updated: 2023-01-31  Resolved: 2023-01-31

Status: Closed
Project: MariaDB Server
Component/s: Backup
Affects Version/s: 10.4.26
Fix Version/s: 10.4.27

Type: Bug Priority: Major
Reporter: YURII KANTONISTOV Assignee: Timofey Turenko
Resolution: Duplicate Votes: 0
Labels: regression
Environment:

NAME="CentOS Linux"
VERSION="7 (Core)"

Attachments: Text File e1.txt     Text File e2.txt     Text File gstack_mariabackup_2_threads_hanging.txt    

 Description   

Issue was first noticed when upgraded MariaDB 10.4.21 => 10.4.22.
Verified now 10.4.26 behaves the same way.
***********

When running mariabackup in single threaded mode - no issue:

# mariabackup -u mysql -pxxx --backup --compress --compress-threads=1 --parallel=1 --stream=xbstream --extra-lsndir=/mysql_backup/ --target-dir=/mysql_backup/ --tmpdir=/tmp/database > /mysql_backup/d1.bkp 2> /tmp/e1.txt

=>
# ls -lha /mysql_backup/d1.bkp
rw-rr-. 1 root root 759M Oct 11 12:01 /mysql_backup/d1.bkp

When running mariabackup with 2 threads - hangs forever:

# mariabackup -u mysql -pxxx --backup --compress --compress-threads=2 --parallel=2 --stream=xbstream --extra-lsndir=/mysql_backup/ --target-dir=/mysql_backup/ --tmpdir=/tmp/database > /mysql_backup/d2.bkp 2> /tmp/e2.txt

Attached mariabackup logs from both single threaded (e1.txt) and 2-threaded (e2.txt) sessions.
Attached also gstack taken from hanging case - gstack_mariabackup_2_threads_hanging.txt

 Comments   
Comment by Elena Stepanova [ 2022-10-11 ]

It should be a duplicate of MDEV-29043 fixed in 10.4.27 (not released yet).

tturenko, could you please double-check that it's a duplicate, and add both original mariabackup calls with their parameter combinations (from this bug report and from MDEV-29043) to the tests if they aren't there yet, as these are real-world scenarios.

Comment by Timofey Turenko [ 2023-01-31 ]

confirmed reproducible with 10.4.26 and not reproducible with 10.4.27.

regression test creation - a separate issue is created TODO-3779

Comment by Timofey Turenko [ 2023-01-31 ]

confirmed: duplicate and it is not reproducible with 10.4.27

Comment by Timofey Turenko [ 2023-01-31 ]

btw, according https://mariadb.com/kb/en/mariabackup-options/#-compress `--compress` option is deprecated starting with 10.1.31

This option is deprecated staring with MariaDB 10.1.31 and 10.2.13 as relies on the no longer maintained QuickLZ library. It is recommended to instead backup to a stream (stdout), and use a 3rd party compression library to compress the stream, as described in Using Encryption and Compression Tools With Mariabackup.

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