We are running the squid proxy for servicing outbound HTTP quests from our network and have observed a significant memory leak with 5.x versions. While there are several discussions about memory leaks with recent versions, just wanted to list out what we have observed in case this is an unknown leak.
- The request-rate through our squid proxy currently ranges between a daily low of 10 rps to a daily high 125 rps.
- About mid-way during the daily ramp in request rates, the memory usage of the squid proxy starts to increase by about 1-2.5 G / day before leveling off till the next day's ramp in reqs. 4.17 does not exhibit this memory leak (or at least not at anything close to this rate).
- We are running 30 squid workers and the cache is set to deny all. Besides this, we have a single tcp_outgoing_address, some site specific ACL’s (both IP & domain acl's), and a custom access log format with a UDP target.
- Both versions of squid run on similar hosts (64 cores each) and receive identical traffic patterns throughout the day. Version 5.3 & 5.1 have similar rates of memory leak.
We are unable to use version 5.X in our production environment as we will have a much higher rate of requests through the proxy later on.
Due to the nature of the memory leak, it appears something with the memory pool management has been broken with version 5.x.
I have attempted to build squid with -with-valgrind-debug, and run it in a test env. However valgrind appears to collect some data from the parse config functions and then the squid proxy restarts. Valgrind no longer reports memory leak stats afterwards.
Snips from squid-internal-mgr/info. Note the data below does not appear to account for all the memory used by the squid process(es), which is also reported by the squid-exporter container. Our node level stats show that the 5.x squid is currently using up more than 28G, while the 4.17 version is under 7G. Both instances were setup to take traffic about 10 days ago.
Thanks
Praveen
Version 5.3
——————
Memory accounted for:
Total accounted: 1215892 KB
memPoolAlloc calls: 7529400915
memPoolFree calls: 7624989161
File descriptor usage for squid:
Maximum number of file descriptors: 31457280
Largest file desc currently in use: 24962
Number of file desc currently in use: 4486
Files queued for open: 0
Available number of file descriptors: 31452794
Reserved number of file descriptors: 3000
Store Disk files open: 0
Version 4.17
——————
Memory accounted for:
Total accounted: 76878 KB
memPoolAlloc calls: 6217787434
memPoolFree calls: 6301483686
File descriptor usage for squid:
Maximum number of file descriptors: 31457280
Largest file desc currently in use: 20184
Number of file desc currently in use: 4419
Files queued for open: 0
Available number of file descriptors: 31452861
Reserved number of file descriptors: 3000
Store Disk files open: 0
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