With threaded on, SIGSEGV occurs during a dry run

[soukichi]

Bug Report

Describe the bug
With threaded on, SIGSEGV occurs during a dry run

To Reproduce

• /etc/fluent-bit/fluent-bit.conf

[SERVICE]
    flush        1
    daemon      Off
    log_level    info

    parsers_file parsers.conf
    plugins_file plugins.conf
    http_server  On
    http_listen  0.0.0.0
    http_port    2020

[INPUT]
    name cpu
    tag  cpu.local
    interval_sec 1
    threaded on
[OUTPUT]
    name  stdout
    match *

$ sudo /opt/fluent-bit/bin/fluent-bit -c /etc/fluent-bit/fluent-bit.conf --dry-run
Fluent Bit v3.1.7
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  __  
|  ___| |                | |   | ___ (_) |         |____ |/  | 
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`| | 
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \ | | 
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /_| |_
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)___/

configuration test is successful
[2024/09/05 17:53:57] [engine] caught signal (SIGSEGV)
#0  0x64644873e28e      in  flb_input_exit_all() at src/flb_input.c:1341
#1  0x646448759c6c      in  flb_engine_shutdown() at src/flb_engine.c:1121
#2  0x646448732694      in  flb_destroy() at src/flb_lib.c:240
#3  0x64644869afeb      in  flb_main() at src/fluent-bit.c:1360
#4  0x7c24ad22a1c9      in  __libc_start_call_main() at libc_start_call_main.h:58
#5  0x7c24ad22a28a      in  __libc_start_main_impl() at t.c:360
#6  0x646448698bd4      in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0
Aborted

remove "threaded on", it works.

$ sudo /opt/fluent-bit/bin/fluent-bit -c /etc/fluent-bit/fluent-bit.conf --dry-run
Fluent Bit v3.1.7
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  __  
|  ___| |                | |   | ___ (_) |         |____ |/  | 
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`| | 
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \ | | 
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /_| |_
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)___/

configuration test is successful

Expected behavior
--dry-run should work with threaded on

Your Environment

• Version used: v3.1.7
• Operating System and version: "Ubuntu 24.04 LTS" 6.8.0-38-generic

[patrick-stephens]

This also fails with the container image when using --dry-run but works fine when using the actual config, i.e. not a dry run.

$ docker run --rm -it -v $PWD/fluent-bit.conf:/fluent-bit/etc/fluent-bit.conf:ro fluent/fluent-bit:3.1.7 -c /fluent-bit/etc/fluent-bit.conf --dry-run 
Fluent Bit v3.1.7
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  __  
|  ___| |                | |   | ___ (_) |         |____ |/  | 
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`| | 
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \ | | 
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /_| |_
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)___/

configuration test is successful
[2024/09/06 10:01:36] [engine] caught signal (SIGSEGV)
#0  0xaaaae293bd9b      in  flb_input_exit_all() at src/flb_input.c:1341
#1  0xaaaae2951fbb      in  flb_engine_shutdown() at src/flb_engine.c:1121
#2  0xaaaae2930c4f      in  flb_destroy() at src/flb_lib.c:240
#3  0xaaaae28c693f      in  flb_main() at src/fluent-bit.c:1360
#4  0xffff7f47777f      in  ???() at ???:0
#5  0xffff7f477857      in  ???() at ???:0
#6  0xaaaae28c466f      in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0

$ cat fluent-bit.conf 
[SERVICE]
    flush        1
    daemon      Off
    log_level    info

    parsers_file parsers.conf
    plugins_file plugins.conf
    http_server  On
    http_listen  0.0.0.0
    http_port    2020

[INPUT]
    name cpu
    tag  cpu.local
    interval_sec 1
    threaded on
[OUTPUT]
    name  stdout
    match *

[patrick-stephens]

Removing the threaded on config option works fine with and without dry run then.

[patrick-stephens]

Using the debug image also fails:

docker run --rm -it -v $PWD/fluent-bit.conf:/fluent-bit/etc/fluent-bit.conf:ro fluent/fluent-bit:3.1.7-debug /fluent-bit/bin/fluent-bit -c /fluent-bit/etc/fluent-bit.conf --dry-run
Fluent Bit v3.1.7
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  __  
|  ___| |                | |   | ___ (_) |         |____ |/  | 
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`| | 
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \ | | 
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /_| |_
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)___/

configuration test is successful
[2024/09/06 10:04:21] [engine] caught signal (SIGSEGV)
#0  0xaaaaabecbd9b      in  flb_input_exit_all() at src/flb_input.c:1341
#1  0xaaaaabee1fbb      in  flb_engine_shutdown() at src/flb_engine.c:1121
#2  0xaaaaabec0c4f      in  flb_destroy() at src/flb_lib.c:240
#3  0xaaaaabe5693f      in  flb_main() at src/fluent-bit.c:1360
#4  0xffff9887773f      in  __libc_start_call_main() at libc_start_call_main.h:58
#5  0xffff98877817      in  __libc_start_main_impl() at t.c:360
#6  0xaaaaabe5466f      in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0