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Disable GC inside coroutines on mac OS
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yorickvP authored and Théophane Hufschmitt committed Apr 7, 2023
1 parent 81dfc2b commit 2c53ef1
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Showing 3 changed files with 63 additions and 5 deletions.
20 changes: 20 additions & 0 deletions src/libexpr/eval.cc
Original file line number Diff line number Diff line change
Expand Up @@ -345,6 +345,20 @@ static Symbol getName(const AttrName & name, EvalState & state, Env & env)
}


class BoehmDisableGC : public DisableGC {
public:
BoehmDisableGC() {
#if HAVE_BOEHMGC
GC_disable();
#endif
};
virtual ~BoehmDisableGC() override {
#if HAVE_BOEHMGC
GC_enable();
#endif
};
};

static bool gcInitialised = false;

void initGC()
Expand All @@ -368,6 +382,12 @@ void initGC()

StackAllocator::defaultAllocator = &boehmGCStackAllocator;


/* Used to disable GC when entering coroutines on macOS */
DisableGC::create = []() {
return std::dynamic_pointer_cast<DisableGC>(std::make_shared<BoehmDisableGC>());
};

/* Set the initial heap size to something fairly big (25% of
physical RAM, up to a maximum of 384 MiB) so that in most cases
we don't need to garbage collect at all. (Collection has a
Expand Down
38 changes: 33 additions & 5 deletions src/libutil/serialise.cc
Original file line number Diff line number Diff line change
Expand Up @@ -186,6 +186,10 @@ static DefaultStackAllocator defaultAllocatorSingleton;
StackAllocator *StackAllocator::defaultAllocator = &defaultAllocatorSingleton;


std::shared_ptr<DisableGC> (*DisableGC::create)() = []() {
return std::dynamic_pointer_cast<DisableGC>(std::make_shared<DisableGC>());
};

std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
{
struct SourceToSink : FinishSink
Expand All @@ -206,7 +210,11 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
if (in.empty()) return;
cur = in;

if (!coro)
if (!coro) {
#if __APPLE__
/* Disable GC when entering the coroutine on macOS, since it doesn't find the main thread stack in this case */
auto disablegc = DisableGC::create();
#endif
coro = coro_t::push_type(VirtualStackAllocator{}, [&](coro_t::pull_type & yield) {
LambdaSource source([&](char *out, size_t out_len) {
if (cur.empty()) {
Expand All @@ -223,17 +231,28 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
});
fun(source);
});
}

if (!*coro) { abort(); }

if (!cur.empty()) (*coro)(false);
if (!cur.empty()) {
#if __APPLE__
auto disablegc = DisableGC::create();
#endif
(*coro)(false);
}
}

void finish() override
{
if (!coro) return;
if (!*coro) abort();
(*coro)(true);
{
#if __APPLE__
auto disablegc = DisableGC::create();
#endif
(*coro)(true);
}
if (*coro) abort();
}
};
Expand Down Expand Up @@ -264,18 +283,27 @@ std::unique_ptr<Source> sinkToSource(

size_t read(char * data, size_t len) override
{
if (!coro)
if (!coro) {
#if __APPLE__
auto disablegc = DisableGC::create();
#endif
coro = coro_t::pull_type(VirtualStackAllocator{}, [&](coro_t::push_type & yield) {
LambdaSink sink([&](std::string_view data) {
if (!data.empty()) yield(std::string(data));
});
fun(sink);
});
}

if (!*coro) { eof(); abort(); }

if (pos == cur.size()) {
if (!cur.empty()) (*coro)();
if (!cur.empty()) {
#if __APPLE__
auto disablegc = DisableGC::create();
#endif
(*coro)();
}
cur = coro->get();
pos = 0;
}
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10 changes: 10 additions & 0 deletions src/libutil/serialise.hh
Original file line number Diff line number Diff line change
Expand Up @@ -551,4 +551,14 @@ struct StackAllocator {
static StackAllocator *defaultAllocator;
};

/* Disabling GC when entering a coroutine (on macos).
::create is to avoid boehm gc dependency in libutil.
*/
class DisableGC {
public:
DisableGC() {};
virtual ~DisableGC() {};
static std::shared_ptr<DisableGC> (*create)();
};

}

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