Re: [squid-users] Squid does not respond to TCP SYN when there are thousands of connection

Hi Amos,

2013/2/15 Amos Jeffries <squid3_at_treenet.co.nz>:
> On 15/02/2013 10:43 p.m., dahanhsi wrote:
>>
>> Thanks for your reply,
>> provide more information below:
>>
>> 2013/2/15 Amos Jeffries <squid3_at_treenet.co.nz>:
>>>
>>> On 15/02/2013 10:12 p.m., dahanhsi wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I use squid as a reverse proxy, and make thousands of connection to the
>>>> it.
>>>
>>> Which version of Squid?
>>
>> I use Squid 2.7
>
>
>
> Output of "squid -v" please.
# squid -v
Squid Cache: Version 2.7.STABLE9
configure options: '--prefix=/usr' '--exec_prefix=/usr'
'--bindir=/usr/sbin' '--sbindir=/usr/sbin'
'--libexecdir=/usr/lib/squid' '--sysconfdir=/etc/squid'
'--localstatedir=/var/spool/squid' '--datadir=/usr/share/squid'
'--enable-async-io' '--with-pthreads'
'--enable-storeio=ufs,aufs,coss,diskd,null' '--enable-linux-netfilter'
'--enable-arp-acl' '--enable-epoll'
'--enable-removal-policies=lru,heap' '--enable-snmp'
'--enable-delay-pools' '--enable-htcp' '--enable-cache-digests'
'--enable-underscores' '--enable-referer-log' '--enable-useragent-log'
'--enable-auth=basic,digest,ntlm,negotiate'
'--enable-negotiate-auth-helpers=squid_kerb_auth' '--enable-carp'
'--enable-follow-x-forwarded-for' '--with-large-files'
'--with-maxfd=65536' 'amd64-debian-linux'
'build_alias=amd64-debian-linux' 'host_alias=amd64-debian-linux'
'target_alias=amd64-debian-linux' 'CFLAGS=-Wall -g -O2'
'LDFLAGS=-Wl,-Bsymbolic-functions' 'CPPFLAGS='

>
>
>
>>
>>> What do you mean by "thousands of connections". 1's of tousands? 10's of
>>> thousands? 100's of thousands?
>>
>> # netstat -nat|grep -i "80"|wc -l
>> the result vary from 4651 to 9404
>>
>>>
>>>> There are one ten of all connections can not establish in TCP layer,
>>>> because squid does not respond SYN-ACK to client's SYN packet. How can
>>>> I solve it?
>>>> Thanks
>>>
>>>
>>> Check ulimit settings for Squid?
>>>
>> # ulimit -a
>> core file size (blocks, -c) 0
>> data seg size (kbytes, -d) unlimited
>> scheduling priority (-e) 20
>> file size (blocks, -f) unlimited
>> pending signals (-i) 16382
>> max locked memory (kbytes, -l) 64
>> max memory size (kbytes, -m) unlimited
>> open files (-n) 655360
>> pipe size (512 bytes, -p) 8
>> POSIX message queues (bytes, -q) 819200
>> real-time priority (-r) 0
>> stack size (kbytes, -s) 8192
>> cpu time (seconds, -t) unlimited
>> max user processes (-u) unlimited
>> virtual memory (kbytes, -v) unlimited
>> file locks (-x) unlimited
>>
>>> Check your cache.log for messages about running out of filedescriptors?
>>
>> I set my limit.conf to:
>> root soft nofile 655360
>> root hard nofile 655360
>
>
> That does not answer the question. Squid may have been built or configured
> with a limit of less than 655360 filedescriptors.
> cache.log should tell you if Squid is reaching some limit like this.
my cache.log:
2013/02/15 8:30:10| Starting Squid Cache version 2.7.STABLE9 for
x86_64-debian-linux-gnu...
2013/02/15 8:30:10| Process ID 8136
2013/02/15 8:30:10| With 2048 file descriptors available
2013/02/15 8:30:10| Using epoll for the IO loop
2013/02/15 8:30:10| DNS Socket created at 0.0.0.0, port 6450, FD 6
2013/02/15 8:30:10| Adding nameserver 8.8.8.8 from /etc/resolv.conf
2013/02/15 8:30:10| User-Agent logging is disabled.
2013/02/15 8:30:10| Referer logging is disabled.
2013/02/15 8:30:10| logfileOpen: opening log /var/log/squid/access.log
2013/02/15 8:30:10| Unlinkd pipe opened on FD 12
2013/02/15 8:30:10| Swap maxSize 8192 + 8388608 KB, estimated 645907 objects
2013/02/15 8:30:10| Target number of buckets: 32295
2013/02/15 8:30:10| Using 32768 Store buckets
2013/02/15 8:30:10| Max Mem size: 8388608 KB
2013/02/15 8:30:10| Max Swap size: 8192 KB
2013/02/15 8:30:10| Local cache digest enabled; rebuild/rewrite every
3600/3600 sec
2013/02/15 8:30:10| logfileOpen: opening log /var/log/squid/store.log
2013/02/15 8:30:10| Rebuilding storage in /var/spool/squid (CLEAN)
2013/02/15 8:30:10| Using Least Load store dir selection
2013/02/15 8:30:10| Set Current Directory to /var/spool/squid
2013/02/15 8:30:10| Loaded Icons.
2013/02/15 8:30:10| Accepting accelerated HTTP connections at 0.0.0.0,
port 80, FD 14.
2013/02/15 8:30:10| Accepting ICP messages at 0.0.0.0, port 3130, FD 15.
2013/02/15 8:30:10| HTCP Disabled.
2013/02/15 8:30:10| WCCP Disabled.
2013/02/15 8:30:10| Configuring localhost Parent localhost/12080/0
2013/02/15 8:30:10| Ready to serve requests.
2013/02/15 8:30:10| Done reading /var/spool/squid swaplog (11 entries)
2013/02/15 8:30:10| Finished rebuilding storage from disk.
2013/02/15 8:30:10| 11 Entries scanned
2013/02/15 8:30:10| 0 Invalid entries.
2013/02/15 8:30:10| 0 With invalid flags.
2013/02/15 8:30:10| 11 Objects loaded.
2013/02/15 8:30:10| 0 Objects expired.
2013/02/15 8:30:10| 0 Objects cancelled.
2013/02/15 8:30:10| 0 Duplicate URLs purged.
2013/02/15 8:30:10| 0 Swapfile clashes avoided.
2013/02/15 8:30:10| Took 0.3 seconds ( 41.8 objects/sec).
2013/02/15 8:30:10| Beginning Validation Procedure
2013/02/15 8:30:10| Completed Validation Procedure
2013/02/15 8:30:10| Validated 11 Entries
2013/02/15 8:30:10| store_swap_size = 44k
2013/02/15 8:30:11| storeLateRelease: released 0 objects
2013/02/15 8:30:35| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'
2013/02/15 8:30:39| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'
2013/02/15 8:30:40| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'
2013/02/15 8:30:42| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'
2013/02/15 8:30:44| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'
2013/02/15 8:33:10| CACHEMGR: <unknown>@127.0.0.1 requesting 'info'

when connection timeout error occurred, I do not see error about file
descriptor.

my /etc/sysclt.conf
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 30
fs.file-max = 65536

my squid.conf has:
max_filedescriptors 2048

and my squidclient says:
squidclient -p 80 mgr:info | grep "file desc"
Maximum number of file descriptors: 2048
Available number of file descriptors: 1651
Reserved number of file descriptors: 100

>
> Amos
Received on Fri Feb 15 2013 - 10:53:40 MST