Squid: WARNING! Your cache is running out of filedescriptors

So you have a LAN with 50+ users and you set up a nice Squid w3cache as a transparent proxy with 100GB of space reserved for the cache (hdds are so cheap nowadays…). Weeks pass and suddenly you notice that something is messing up your web experience as Firefox suddenly decides to run painfully slow. About 30 minutes wasted on finding the culprit (like changing your DNS servers, clearing browser cache, etc.) until you decide to check the router and then the Squid with its logs. And then you find something fishy:

2007/01/01 17:51:19| WARNING! Your cache is running out of filedescriptors
2007/01/01 17:51:35| WARNING! Your cache is running out of filedescriptors
2007/01/01 17:51:51| WARNING! Your cache is running out of filedescriptors

I won’t be explaining why this happens. Others have done it before. What I’m going to do is present you with a solution that does not require a complete Squid recompilation/reinstallation procedure.


/etc/init.d/squid stop

nano /etc/squid/squid.conf
  max_filedesc 4096

nano /etc/init.d/squid
  # add this just after the comments (before any script code)
  ulimit -HSn 4096

/etc/init.d/squid start


nano /etc/defaults/squid

/etc/init.d/squid restart


nano /etc/default/squid

/etc/init.d/squid restart

And now watch the /var/log/squid/cache.log for a similar line:

2007/01/01 18:32:27 With 4096 file descriptors available

If it still says 1024 file descriptors available (or similarly low value) you are out of luck (or you’ve just messed something up).

Published by

Paweł Gościcki

Ruby/Rails programmer.

15 thoughts on “Squid: WARNING! Your cache is running out of filedescriptors”

  1. Surely the editing of /usr/include/bits/typesizes.h is unnecessary if you don’t recompile Squid (and anyway, that version of Squid doesn’t need to have that file changes anyway, as its configure script has a –maxfd option).

    I was certainly able to up my FC6’s squid installation to use 2048 descriptors by changing just /etc/init.d/squid and /etc/squid/squid.conf

  2. Thanks a bunch. Using /etc/defaults/squid in Squid is the most trivial place to find but somehow I looked in the wrong places. Pushing that from 1024 to 4096 instantly got my users happy. :)

  3. Thank’s guys. This is great … (I’ve had exactly the same problem, but resolved). Again thank’s …

  4. Thanks mate. I was guessing for the worse, like someone is ddos-ing my squid.

  5. Thanks alot. It helped me in IPCOP.

    I used this command : SQUID_MAXFD=4096
    while squid was stopped and then I started the squid and it works fine now.

    Thanks a bunch again. Keep it Up Please.

  6. Omygosh, thank you, thank you, thank you, this saved me and my users so much heartache!

    Slight typo in the Debian instructions, the squid restart command should read:
    /etc/init.d/squid restart

  7. Thank you so much…

    I’m using IPCOP 1.4.21 + Advanced Proxy

    add this line:


    in /var/ipcop/proxy/advanced/acls/include.acl

    and the warning lines are history…

  8. current ubuntu 10.04 (lts) has a bug an so setting SQUID_MAXFD in /etc/default/squid does not work.

    i changed the following line in squid.conf:
    from: # max_filedescriptors 0
    to: max_filedescriptors 8128

    restarted squid, and it works:
    2010/11/13 18:24:18| Starting Squid Cache version 2.7.STABLE7 for amd64-debian-linux-gnu…
    2010/11/13 18:24:18| Process ID 3312
    2010/11/13 18:24:18| With 8128 file descriptors available

    ubuntu bug report:

  9. thanks for the great tip, it sorted out our problem, 150+ local users, 400GB of cache space, hit the wall at 266G cached..

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