46b6907346
This reverts commit4b3ca9bd80, reversing changes made to867b69f533. Since this commit we get reproducible segfaults building Nix ci in macos github runners: https://github.com/NixOS/nix/actions/runs/16885882321/job/47837390248
129 lines
3.5 KiB
C++
129 lines
3.5 KiB
C++
#include "nix/util/error.hh"
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#include "nix/util/environment-variables.hh"
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#include "nix/expr/eval-settings.hh"
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#include "nix/util/config-global.hh"
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#include "nix/util/serialise.hh"
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#include "nix/expr/eval-gc.hh"
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#include "nix/expr/value.hh"
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#include "expr-config-private.hh"
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#if NIX_USE_BOEHMGC
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# include <pthread.h>
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# ifdef __FreeBSD__
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# include <pthread_np.h>
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# endif
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# include <gc/gc_allocator.h>
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# include <boost/coroutine2/coroutine.hpp>
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# include <boost/coroutine2/protected_fixedsize_stack.hpp>
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# include <boost/context/stack_context.hpp>
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#endif
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namespace nix {
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#if NIX_USE_BOEHMGC
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/* Called when the Boehm GC runs out of memory. */
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static void * oomHandler(size_t requested)
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{
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/* Convert this to a proper C++ exception. */
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throw std::bad_alloc();
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}
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static inline void initGCReal()
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{
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/* Initialise the Boehm garbage collector. */
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/* Don't look for interior pointers. This reduces the odds of
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misdetection a bit. */
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GC_set_all_interior_pointers(0);
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/* We don't have any roots in data segments, so don't scan from
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there. */
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GC_set_no_dls(1);
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/* Enable perf measurements. This is just a setting; not much of a
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start of something. */
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GC_start_performance_measurement();
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GC_INIT();
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/* Enable parallel marking. */
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GC_allow_register_threads();
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/* Register valid displacements in case we are using alignment niches
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for storing the type information. This way tagged pointers are considered
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to be valid, even when they are not aligned. */
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if constexpr (detail::useBitPackedValueStorage<sizeof(void *)>)
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for (std::size_t i = 1; i < sizeof(std::uintptr_t); ++i)
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GC_register_displacement(i);
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GC_set_oom_fn(oomHandler);
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/* Set the initial heap size to something fairly big (25% of
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physical RAM, up to a maximum of 384 MiB) so that in most cases
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we don't need to garbage collect at all. (Collection has a
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fairly significant overhead.) The heap size can be overridden
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through libgc's GC_INITIAL_HEAP_SIZE environment variable. We
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should probably also provide a nix.conf setting for this. Note
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that GC_expand_hp() causes a lot of virtual, but not physical
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(resident) memory to be allocated. This might be a problem on
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systems that don't overcommit. */
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if (!getEnv("GC_INITIAL_HEAP_SIZE")) {
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size_t size = 32 * 1024 * 1024;
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# if HAVE_SYSCONF && defined(_SC_PAGESIZE) && defined(_SC_PHYS_PAGES)
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size_t maxSize = 384 * 1024 * 1024;
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long pageSize = sysconf(_SC_PAGESIZE);
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long pages = sysconf(_SC_PHYS_PAGES);
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if (pageSize != -1)
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size = (pageSize * pages) / 4; // 25% of RAM
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if (size > maxSize)
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size = maxSize;
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# endif
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debug("setting initial heap size to %1% bytes", size);
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GC_expand_hp(size);
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}
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}
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static size_t gcCyclesAfterInit = 0;
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size_t getGCCycles()
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{
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assertGCInitialized();
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return static_cast<size_t>(GC_get_gc_no()) - gcCyclesAfterInit;
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}
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#endif
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static bool gcInitialised = false;
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void initGC()
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{
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if (gcInitialised)
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return;
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#if NIX_USE_BOEHMGC
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initGCReal();
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gcCyclesAfterInit = GC_get_gc_no();
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#endif
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// NIX_PATH must override the regular setting
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// See the comment in applyConfig
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if (auto nixPathEnv = getEnv("NIX_PATH")) {
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globalConfig.set("nix-path", concatStringsSep(" ", EvalSettings::parseNixPath(nixPathEnv.value())));
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}
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gcInitialised = true;
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}
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void assertGCInitialized()
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{
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assert(gcInitialised);
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}
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} // namespace nix
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