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Track function start and ends for flame graphs

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With this patch, and this file I called `log.py`:

    #!/usr/bin/env nix-shell
    #!nix-shell -i python3 -p python3 --pure

    import sys
    from pprint import pprint

    stack = []
    timestack = []

    for line in open(sys.argv[1]):
        components = line.strip().split(" ", 2)
        if components[0] != "function-trace":
            continue

        direction = components[1]
        components = components[2].rsplit(" ", 2)

        loc = components[0]
        _at = components[1]
        time = int(components[2])

        if direction == "entered":
            stack.append(loc)
            timestack.append(time)
        elif direction == "exited":
            dur = time - timestack.pop()
            vst = ";".join(stack)
            print(f"{vst} {dur}")
            stack.pop()

and:

    nix-instantiate --trace-function-calls -vvvv ../nixpkgs/pkgs/top-level/release.nix -A unstable > log.matthewbauer 2>&1
    ./log.py ./log.matthewbauer > log.matthewbauer.folded
    flamegraph.pl --title matthewbauer-post-pr log.matthewbauer.folded > log.matthewbauer.folded.svg

I can make flame graphs like: http://gsc.io/log.matthewbauer.folded.svg

---

Includes test cases around function call failures and tryEval. Uses
RAII so the finish is always called at the end of the function.
This commit is contained in:
Graham Christensen 2019-04-12 12:31:33 -04:00
parent 1eeaf99cf8
commit ee9c988a1b
No known key found for this signature in database
GPG key ID: ACA1C1D120C83D5C
7 changed files with 189 additions and 3 deletions
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8
src/libexpr/eval.cc
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@ -9,6 +9,7 @@
#include "json.hh"
#include <algorithm>
#include <chrono>
#include <cstring>
#include <unistd.h>
#include <sys/time.h>
@ -16,7 +17,6 @@
#include <iostream>
#include <fstream>
#include <sys/time.h>
#include <sys/resource.h>
#if HAVE_BOEHMGC
@ -1094,9 +1094,13 @@ void EvalState::callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos)
}
}
void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & pos)
{
std::optional<FunctionCallTrace> trace;
if (evalSettings.traceFunctionCalls) {
trace.emplace(pos);
}
forceValue(fun, pos);
if (fun.type == tPrimOp || fun.type == tPrimOpApp) {