Cache is not respecting the provided size

[jaredririe]

I create a new cache with a size of 100MB and set the GC percentage as recommended in the readme to 20%.

cacheSize := 100 * 1024 * 1024 // 100MB
cache := freecache.NewCache(cacheSize)
debug.SetGCPercent(20)

Despite this, the cache grows like a memory leak beyond the 100MB I specified. After a few days of use, it is using ~1.2 GB, as indicated by profiling the heap. The machine has just 3 GB of memory, so this is significant.

      flat  flat%   sum%        cum   cum%
 1278.15MB 98.40% 98.40%  1278.15MB 98.40%  .../vendor/github.com/coocood/freecache.NewRingBuf /go/src/.../vendor/github.com/coocood/freecache/ringbuf.go (inline)
   13.55MB  1.04% 99.44%  1291.70MB 99.44% .../vendor/github.com/coocood/freecache.newSegment /go/src/.../vendor/github.com/coocood/freecache/segment.go (inline)

[coocood]

Can you give me some detail about how the cache is used?
Does it call Clear multiple times during the usage?

[coocood]

Are you sure there is only one cache created?

[jaredririe]

Are you sure there is only one cache created?

Your question prompted a deep dive into this part of the code and I realized it is possible for multiple caches to be created in a particular case. I pushed out of a fix and will monitor the memory usage over the next day. I believe this is the root cause.

[jaredririe]

The fix to ensure only one cache can ever be created has been live for a day now, and the memory usage for the cache is right at the requested 100MB. Thanks for the suggestion!