Merge pull request #8895 from hercules-ci/gc-before-stats

eval: Run a full GC before printing stats

(cherry picked from commit aeea49609be014b1928c95b7ec28dbedeb4f032a)
Change-Id: I47a23d3a7a47ea61d9a2b5727b638f879f3aaf1e
This commit is contained in:
eldritch horrors 2024-03-04 04:08:28 +01:00
parent fd1299cef3
commit 6feba52008
6 changed files with 141 additions and 99 deletions

View file

@ -98,7 +98,7 @@ EvalCommand::EvalCommand()
EvalCommand::~EvalCommand()
{
if (evalState)
evalState->printStats();
evalState->maybePrintStats();
}
ref<Store> EvalCommand::getEvalStore()

View file

@ -2477,10 +2477,37 @@ bool EvalState::eqValues(Value & v1, Value & v2, const PosIdx pos, std::string_v
}
}
void EvalState::printStats()
bool EvalState::fullGC() {
#if HAVE_BOEHMGC
GC_gcollect();
// Check that it ran. We might replace this with a version that uses more
// of the boehm API to get this reliably, at a maintenance cost.
// We use a 1K margin because technically this has a race condtion, but we
// probably won't encounter it in practice, because the CLI isn't concurrent
// like that.
return GC_get_bytes_since_gc() < 1024;
#else
return false;
#endif
}
void EvalState::maybePrintStats()
{
bool showStats = getEnv("NIX_SHOW_STATS").value_or("0") != "0";
if (showStats) {
// Make the final heap size more deterministic.
#if HAVE_BOEHMGC
if (!fullGC()) {
warn("failed to perform a full GC before reporting stats");
}
#endif
printStatistics();
}
}
void EvalState::printStatistics()
{
struct rusage buf;
getrusage(RUSAGE_SELF, &buf);
float cpuTime = buf.ru_utime.tv_sec + ((float) buf.ru_utime.tv_usec / 1000000);
@ -2494,7 +2521,7 @@ void EvalState::printStats()
GC_word heapSize, totalBytes;
GC_get_heap_usage_safe(&heapSize, 0, 0, 0, &totalBytes);
#endif
if (showStats) {
auto outPath = getEnv("NIX_SHOW_STATS_PATH").value_or("-");
std::fstream fs;
if (outPath != "-")
@ -2594,7 +2621,6 @@ void EvalState::printStats()
fs << topObj.dump(2) << std::endl;
}
}
}
std::string ExternalValueBase::coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const

View file

@ -709,9 +709,25 @@ public:
void concatLists(Value & v, size_t nrLists, Value * * lists, const PosIdx pos, std::string_view errorCtx);
/**
* Print statistics.
* Print statistics, if enabled.
*
* Performs a full memory GC before printing the statistics, so that the
* GC statistics are more accurate.
*/
void printStats();
void maybePrintStats();
/**
* Print statistics, unconditionally, cheaply, without performing a GC first.
*/
void printStatistics();
/**
* Perform a full memory garbage collection - not incremental.
*
* @return true if Nix was built with GC and a GC was performed, false if not.
* The return value is currently not thread safe - just the return value.
*/
bool fullGC();
/**
* Realise the given context, and return a mapping from the placeholders

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@ -344,7 +344,7 @@ static void main_nix_build(int argc, char * * argv)
}
}
state->printStats();
state->maybePrintStats();
auto buildPaths = [&](const std::vector<DerivedPath> & paths) {
/* Note: we do this even when !printMissing to efficiently

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@ -1531,7 +1531,7 @@ static int main_nix_env(int argc, char * * argv)
op(globals, std::move(opFlags), std::move(opArgs));
globals.state->printStats();
globals.state->maybePrintStats();
return 0;
}

View file

@ -189,7 +189,7 @@ static int main_nix_instantiate(int argc, char * * argv)
evalOnly, outputKind, xmlOutputSourceLocation, e);
}
state->printStats();
state->maybePrintStats();
return 0;
}