[squid-users] squid cache takes a break

Vieri rentorbuy at yahoo.com
Tue Sep 12 10:59:26 UTC 2017

From: Amos Jeffries <squid3 at treenet.co.nz>
> That is all it needs to do to begin with; parse off the numeric value 
> from the input line and send it back as prefix on the output line. The 

> helper does not need threading or anything particularly special for the > minimal support.

I thought it had to be asynchronous.
The docs say "Only used with helpers capable of processing more than one query at a time."

Squid sends "1 URI1" (or whatever) to the helper.
It does not wait for an immediate response.
In fact, Squid can send "2 URI2" before getting the reply to ID 1, right?
In my case, the helper is synchronous, non-MT. I don't think it will improve the time responses per-se.

In any case, my helper won't be able to process more than one query AT A TIME.

I tried it anyway. So here's the relevant code:

while( <STDIN> )
my @squidin = split;
my $squidn = scalar @squidin;
undef $url;
undef $channelid;
if ( ($squidn == 2 ) && (defined $squidin[0]) && ($squidin[0] =~ /^\d+?$/) ) {
$channelid = $squidin[0];
$url = $squidin[1] if (defined $squidin[1]);
} else {
$url = $squidin[0] if (defined $squidin[0]);

logtofile("Channel-ID: ".$channelid."\n") if ((defined $channelid) && ($debug >= 1));

[...do DB lookups, reply accordingly...]

if (defined $channelid) {
print( $channelid." OK\n" );
logtofile( $channelid." OK\n" ) if ($debug >= 1);
} else {
print( "OK\n" );
logtofile( "OK\n" ) if ($debug >= 1);
[...similar responses for ERR messages...]

Here's the relevant squid.conf line:
external_acl_type bllookup ttl=86400 negative_ttl=86400 children-max=80 children-startup=10 children-idle=3 concurrency=8 %URI /opt/custom/scripts/run/scripts/firewall/squid_url_lookup.pl [...]

How can I check in the Squid log that concurrency is "working"?

If the helper logs to a text file as in the trimmed code above, I notice that the channel ID is always 0. I get messages such as:
Channel-ID: 0
0 OK
Channel-ID: 0
0 ERR ...

Is this expected?

Despite this, I can see that the number of helper processes does not increase over time for now, and that HTTP/S client browsing is responsive enough.
# ps aux | grep -c squid_url_lookup.pl

One last thing. I'm using:
cache_dir diskd /var/cache/squid 100 16 256
I may want to try to comment out this directive for improved I/O performance.



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