Memory Tracing

通过设置 GODEBUG 环境变量为 gctrace=1 可以让 golang 的 垃圾回收器 将每次 GC 的结果打印到标准错误输出。^[1]

export GODEBUG=gctrace=1

gc # @#s #%: #+...+# ms clock, #+...+# ms cpu, #->#-># MB, # MB goal, # P

gc #        the GC number, incremented at each GC
@#s         time in seconds since program start
#%          percentage of time spent in GC since program start
#+...+#     wall-clock/CPU times for the phases of the GC
#->#-># MB  heap size at GC start, at GC end, and live heap
# MB goal   goal heap size
# P         number of processors used

若想拿到更细节的并发 pacer 的信息，可以设置 GODEBUG=gctrace=1,gcpacertrace=1。