The GOGC variable sets the initial garbage collection target percentage. A collection is triggered when the ratio of freshly allocated data to live data remaining after the previous collection reaches this percentage. The default is GOGC=100. Setting GOGC=off disables the garbage collector entirely.

默认100, 举例说, 上次GC之后还占用 100M 内存, 那么再次申请新内存到100M的时候, 会触发GC.

设置成50的话, 就是说, 上次GC之后还占用 100M 内存, 那么再次申请新内存到50M的时候, 会触发GC.