input: update mem buf limit logging to include size info

[nuclearpidgeon]

Addresses #10384

Example of new output

> bin/fluent-bit -i tail -p path=./logslurp -p mem_buf_limit=1m -o file -m '*' -H
Fluent Bit v4.0.4
* Copyright (C) 2015-2025 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

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


[2025/07/11 08:47:05] [ info] [fluent bit] version=4.0.4, commit=a4e3d2b20d, pid=71384
[2025/07/11 08:47:05] [ info] [storage] ver=1.5.3, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2025/07/11 08:47:05] [ info] [simd    ] disabled
[2025/07/11 08:47:05] [ info] [cmetrics] version=1.0.3
[2025/07/11 08:47:05] [ info] [ctraces ] version=0.6.6
[2025/07/11 08:47:05] [ info] [input:tail:tail.0] initializing
[2025/07/11 08:47:05] [ info] [input:tail:tail.0] storage_strategy='memory' (memory only)
[2025/07/11 08:47:05] [ info] [output:file:file.0] worker #0 started
[2025/07/11 08:47:05] [ info] [http_server] listen iface=0.0.0.0 tcp_port=2020
[2025/07/11 08:47:05] [ info] [sp] stream processor started
[2025/07/11 08:47:05] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2025/07/11 08:47:05] [ info] [input:tail:tail.0] inotify_fs_add(): inode=8005407 watch_fd=1 name=./logslurp

Dump some contents into ./logslurp by running this a few times:

cat /dev/random | xxd | dd of=./logslurp bs=1M count=1024

and we see this:

[2025/07/11 08:47:47] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:47] [ info] [input] pausing tail.0
[2025/07/11 08:47:47] [ info] [input] resume tail.0
[2025/07/11 08:47:47] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)
[2025/07/11 08:47:47] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:47] [ info] [input] pausing tail.0
[2025/07/11 08:47:48] [ info] [input] resume tail.0
[2025/07/11 08:47:48] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)
[2025/07/11 08:47:48] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:48] [ info] [input] pausing tail.0
[2025/07/11 08:47:49] [ info] [input] resume tail.0
[2025/07/11 08:47:49] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)
[2025/07/11 08:47:49] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:49] [ info] [input] pausing tail.0
[2025/07/11 08:47:50] [ info] [input] resume tail.0
[2025/07/11 08:47:50] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)
[2025/07/11 08:47:50] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:50] [ info] [input] pausing tail.0
[2025/07/11 08:47:51] [ info] [input] resume tail.0
[2025/07/11 08:47:51] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)
[2025/07/11 08:47:51] [ warn] [input] tail.0 paused (mem buf overlimit - event of size 49543B exceeded limit 1000000 to 1040403B)
[2025/07/11 08:47:51] [ info] [input] pausing tail.0
[2025/07/11 08:47:52] [ info] [input] resume tail.0
[2025/07/11 08:47:52] [ info] [input] tail.0 resume (mem buf overlimit - buf size 0B now below limit 1000000B)

Backporting
It would be nice to backport this to latest stable release if it's not too major a change.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[nuclearpidgeon]

cc: @patrick-stephens

[nuclearpidgeon]

Thanks Hiroshi