optimizing nsq

bits.md

From "Lessons Learned Optimizing NSQ"

• https://speakerd.s3.amazonaws.com/presentations/a67a65808c9301319a381659f8c2cbb1/nsq_2014-03-06.pdf

Reducing GC Pressure

• avoid []byte to string conversions
• re-use buffers or objects (use sync.Pool in Go 1.3)
• pre-allocate slices make([]byte, 0, 1024)
• explicitly specify number/size of items on the wire
• leave nothing unbounded
• apply sane limits to configurable dials (message size, # of messages)
• avoid boxing (use of interface{}) or unnecessary wrapper types
• avoid the use of defer in hot code paths (it allocates)

Other lessons learned

don’t be afraid of the sync package

• channels are overkill for primitives
• goroutines are cheap not free (~4k per)
• use worker pools rather than “goroutine per X”
• synchronizing goroutine exit and cleanup is hard
• all IO must have timeouts (guarantee progress)
• wrap IO with bufio.Reader/Writer to reduce context switches (syscalls)
• select skips nil channels