On 07/07/17 13:55, Ivan Larionov wrote:
Hi. Sorry that I'm answering to the old thread. I was on vacation and
didn't have a chance to test the proposed solution.
Dieter, yes, I'm on the old CentOS 6 based OS (Amazon Linux) but with a
new kernel 4.9.27.
Amos, thank you for the suggestions about configure flags and squid
config options, I fixed all issues you pointed to.
Unfortunately following workarounds didn't help:
* client_idle_pconn_timeout 30 seconds
* half_closed_clients on
* client_persistent_connections off
* server_persistent_connections off
TIME_WAIT is a sign that Squid is following the normal TCP process for
closing connections, and doing so before the remote endpoint closes.
Disabling persistent connections increases the number of connections
going through that process. So you definitely want those settings ON to
reduce the WAIT states.
If the remote end is the one doing the closure, then you will see less
TIME_WAIT, but CLOSE_WAIT will increase instead. The trick is in finding
the right balance of timeouts on both client and server idle pconn to
get the minimum of total WAIT states. That is network dependent.
Generally though forward/explicit and intercept proxies want
client_idle_pconn_timeout to be shorter than server_idle_pconn_timeout.
Reverse proxy want the opposite.
However I assumed that this is a bug and that I can find older version
which worked fine. I started testing from 3.1.x all the way to 3.5.26
and this is what I found:
* All versions until 3.5.21 work fine. There no issues with huge amount
of TIME_WAIT connections under load.
* 3.5.20 is the latest stable version.
* 3.5.21 is the first broken version.
* 3.5.23, 3.5.25, 3.5.26 are broken as well.
This effectively means that bug is somewhere in between 3.5.20 and 3.5.21.
I hope this helps and I hope you'll be able to find an issue. If you can
create a bug report based on this information and post it here it would
be awesome.
The changes in 3.5.21 were fixes to some common crashes and better
caching behaviour. So I expect at least some of the change is due to
higher traffic throughput on proxies previously restricted by those
problems.
Amos
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