[syslog-ng] syslog-ng never frees RAM

Thu Sep 6 10:00:15 UTC 2018

Reviewing your commit I've found out that the method *_handle_file_deleted*
seems not to free memory when a monitored file has been deleted, according
to the changes you made in *_handler_handler_directory_deleted.* Could it
be the cause of the memory leak?

Thanks.

2018-09-06 11:50 GMT+02:00 Jose Angel Santiago <jasantiago at stratio.com>:

> Hi,
>
> I was testing your fix in several environments before replying,
> unfortunately syslog-ng stills shows a huge RAM consumption in our use of
> case.
>
> We have two wildcard-file sources defined in our syslog-ng conf file, both
> of them have the same base-dir reference, but one source has a
> filename-pattern and the other source has a different one (I think we can't
> use the same source and several filename-patterns because of the lack of
> regular expression support). We execute the deletion of obsolete files and
> folder under base-dir once every 2 days, and we create a lot of new folders
> and files constantly while using our platform, but the growth of these log
> files (the ones affected by the filename-pattern) has been pretty low in
> this test, about 10-20 msgs per second total.
>
> This is some data of the fix test:
>
> Syslog-ng was consuming 21,7G of RAM with 10600 files affected by the
> filename-pattern and 20000 folders under base-dir (not a single folder were
> deleted yet so this is the expected behaviour of syslog-ng, and we find it
> extremely unaffordable)
>
> One hour later, right before the cleaning process was executed, syslog-ng
> was consuming 35G of RAM, and it didn't decrease after the cleaning, not
> even a little, with just 380 files affected by the filename-pattern and
> 2200 folders under base-dir.
>
> There is no message in the syslog-agent queue and all the messages are
> received by the relay (which ingest messages in an elasticsearch)
>
> For the record, we do noticed a small RAM usage decrease in a previous
> test in a lab environment when we deleted every folder & file under
> base-dir (from 870M to 550M).
>
> It seems syslog-ng wildcard-source is not optimized when it has too handle
> thousands of folders and filename-patterns under base-dir. Have you ever
> test the wildcard-source with a use of case similar to ours?
>
> Can I send you any more information which may help to find out how to
> optimize it? I wish I can help with the code but I have no idea of C
> language :-(
>
> Thanks in advance.
>
>
>
>
> 2018-09-04 18:03 GMT+02:00 Nagy, Gábor <gabor.nagy at oneidentity.com>:
>
>> Hello,
>>
>> Thanks for the thorough investigation!
>> We've checked it and found a memory leak in directory monitoring.
>>
>> I've pushed the fix to my fork and created a merge request about it:
>> https://github.com/gaborznagy/syslog-ng/commits/fix-wildcard-memleak
>> https://github.com/balabit/syslog-ng/pull/2261
>> Can you verify that this fixes your problem, please?
>>
>> > log-fifo-size value is 345000, so I assume it can't be a buffer
>> situation since 345000 messages can't occupy 40-50 GB of memory.
>> Well our default log-msg-size is 64kB so if all messages have a size of
>> log-msg-size then it can be around ~21GB when syslog-ng is buffering.
>>
>> Best Regards,
>> Gabor
>>
>>
>> On Tue, Sep 4, 2018 at 10:50 AM Jose Angel Santiago <
>> jasantiago at stratio.com> wrote:
>>
>>> Hi,
>>>
>>> I'm using syslog-ng 3.16.1 with wildcard-file as source (let's call it
>>> "syslog-agent), which sends log messages to another syslog-ng acting as a
>>> relay.
>>>
>>> I've noticed that syslog-agent instances RAM consumption keeps
>>> increasing until they leave no free memory in the cluster (each server has
>>> 64G of RAM). In my use case, new folders & files are created constantly
>>> under base-dir folder, but every 2 days obsolete folders & files are
>>> deleted. I assumed that syslog-ng would free some RAM every time those
>>> folders & files are deleted, but it doesn't, not even if I run a
>>> syslog-ng-ctl reload operation.
>>>
>>> log-fifo-size value is 345000, so I assume it can't be a buffer
>>> situation since 345000 messages can't occupy 40-50 GB of memory.
>>>
>>> I've performed the following test to reproduce the situation in small
>>> scale:
>>>
>>> - Launch a syslog-agent with a wildcard-file source reading from
>>> "/tmp/test/" base-dir. syslog-agent RAM usage is about 125M.
>>> - Run a simple script to create complex folder hierarchy under /tmp/test
>>> and some files with 5000 log messages to read from.
>>> - Wait until syslog-agent RAM usage gets 1GB
>>> - Stop script execution and wait until syslog-agent has send all logs to
>>> relay.
>>> - Delete everything under /tmp/test and execute syslog-ng-ctl reload
>>> operation
>>> - 24 hours after, syslog-agent RAM usage still is 1GB
>>>
>>> I've used heaptrack tool as a try to find a memory leak in syslog-ng,
>>> you can see in the attached image that iv_list_empty function in iv_list.h
>>> file is where most of the RAM usage is.
>>>
>>> How do I get syslog-ng to free RAM? Or is it a memory leak?
>>>
>>> Thanks in advance.
>>>
>>>
>>> --
>>>
>>> | Jose Angel Santiago
>>>
>>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>>
>>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>>
>>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>>
>>> +34 918 286 473 | www.stratio.com
>>> <https://twitter.com/stratiobd>
>>> <https://www.linkedin.com/company/stratiobd>
>>> <https://www.youtube.com/c/StratioBD>
>>> ____________________________________________________________
>>> __________________
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>>> Documentation: http://www.balabit.com/support/documentation/?product=
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>>>
>>>
>> ____________________________________________________________
>> __________________
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>>
>>
>>
>
>
> --
>
> | Jose Angel Santiago
>
> [image: Logo_signature2.png] <http://www.stratio.com/>
>
> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>
> 28224 Pozuelo de Alarcón, Madrid, Spain
>
> +34 918 286 473 | www.stratio.com
> <https://twitter.com/stratiobd>
> <https://www.linkedin.com/company/stratiobd>
> <https://www.youtube.com/c/StratioBD>
>

-- 

| Jose Angel Santiago

[image: Logo_signature2.png] <http://www.stratio.com/>

Vía de las dos Castillas, 33, Ática 4, 3ª Planta

28224 Pozuelo de Alarcón, Madrid, Spain

+34 918 286 473 | www.stratio.com
<https://twitter.com/stratiobd> <https://www.linkedin.com/company/stratiobd>
<https://www.youtube.com/c/StratioBD>
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