英文:
How can I make pprof show every single function in a call tree?
问题
我正在尝试从https://github.com/greenplum-db/gpbackup获取gpbackup的完整调用树。我使用的是runtime/pprof而不是net/http/pprof，据我所知，收集统计信息不应该有任何时间限制。我在程序的最开始启动pprof服务器，并在os.Exit()命令之前停止它。为了收集统计信息，我运行gpbackup，它按预期工作并生成了cpu.prof输出。然后我使用pprof --nodecount=100000 gpb cpu.prof命令生成调用树，并使用png命令生成图像。问题是调用树缺少大量函数。例如，DoBackup()函数以日志函数开始，但在调用树中缺失，还有许多其他函数似乎也没有出现。我该如何让pprof显示每个单独的调用在调用树中？
英文:
I'm trying to get a full call tree of gpbackup from https://github.com/greenplum-db/gpbackup. I use runtime/pprof, not net/http/pprof, so as far as I know there shouldn't be any time limitations for collecting stats. I start pprof server in a very beginning of a program and stop it right before os.Exit() command. To collect stats I run gpbackup, it works as intended and I get cpu.prof output. Then I use pprof --nodecount=100000 gpb cpu.prof and generate a call tree with png command. The problem is that call tree lacks of major number of functions. For example, DoBackup() starts with logging functions, but they miss in a call tree, and there are lots of other functions that don't seem to appear either. How can I make pprof show every single call in a call tree?
答案1
得分: 0
默认情况下，pprof会删除CPU时间少于0.5%的节点和CPU时间少于0.1%的边。你可以通过提供-nodefraction=0和-edgefraction=0标志来告诉pprof不要这样做，这可能会解决你的问题。
并不完全正确，runtime/pprof每秒采样100次。每次采样时，它会捕获完整的堆栈跟踪。因此，如果某些函数的执行速度快于0.01秒，并且不是较长运行函数的堆栈帧的一部分，你可能会错过这些函数。
你可以复制StartCPUProfile并更改hz变量，以便更频繁地进行采样。
英文:
By default pprof removes nodes with less than 0.5% of the CPU time and edges with less then 0.1% of the CPU time. You can ask pprof to not do this by supplying the -nodefraction=0 and -edgefraction=0 flags, this might solve your issue.
> so as far as I know there shouldn't be any time limitations for collecting stats
Not fully true, runtime/pprof samples 100 times per second. Every time it samples, it captures the full stack-trace. So you might miss functions if they execute faster than 100th of a second and are not part of the stack frame of longer running functions.
You could copy StartCPUProfile and change the hz variable so it captures more often.
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