[squid-users] High utilization of CPU squid-3.5.23,squid-3.5.24

[Vitaly Lavrov]

Periodically squid begins to linearly increase the use of the CPU.
Sometimes this process reaches 100%. At random moment of time the CPU usage is reduced to 5-15%,
and in the presence of client requests can again start linearly increasing use of CPU.

In the protocols are no error messages.

CPU consumption does not correlate with the number of requests and traffic.

The increase CPU consumption from 0 to 60% occurs in about 4-5 hours, and to 100% for 6-8 hours.

A typical graph of CPU usage can be viewed on http://devel.aanet.ru/tmp/squid-cpu-x.png

With the "perf record -p` pgrep -f squid-1` - sleep 30" I have received the following information:

At 100% CPU load most of the time took 3 calls

  49.15% squid squid [.] MemObject :: dump
  25.11% squid squid [.] Mem_hdr :: freeDataUpto
  20.03% squid squid [.] Mem_hdr :: copy

When loading CPU 30-60% most of the time took 3 calls

  37.26% squid squid [.] Mem_node :: dataRange
  22.61% squid squid [.] Mem_hdr :: NodeCompare
  17.31% squid squid [.] Mem_hdr :: freeDataUpto

What is it ? Is it possible to somehow fix it?

System: slackware64 14.2

sslbump not used. http only.

Part of config:

memory_pools off
memory_pools_limit 512 MB
cache_mem 768 MB
maximum_object_size_in_memory 64 KB
cache_dir ufs           /cache/sq_c1 16312 16 256
cache_dir ufs           /cache/sq_c2 16312 16 256
cache_dir ufs           /cache/sq_c3 16312 16 256