Merge pull request #14260 from roberth/ulimit

Clarify setStackSize error message and warn if not possible

Author: Ericson2314

src/libutil/current-process.cc

@@ -7,6 +7,7 @@
 #include "nix/util/file-system.hh"
 #include "nix/util/processes.hh"
 #include "nix/util/signals.hh"
+#include "nix/util/environment-variables.hh"
 #include <math.h>
 
 #ifdef __APPLE__
@@ -65,13 +66,27 @@ void setStackSize(size_t stackSize)
     struct rlimit limit;
     if (getrlimit(RLIMIT_STACK, &limit) == 0 && static_cast<size_t>(limit.rlim_cur) < stackSize) {
         savedStackSize = limit.rlim_cur;
-        limit.rlim_cur = std::min(static_cast<rlim_t>(stackSize), limit.rlim_max);
+        if (limit.rlim_max < static_cast<rlim_t>(stackSize)) {
+            if (getEnv("_NIX_TEST_NO_ENVIRONMENT_WARNINGS") != "1") {
+                logger->log(
+                    lvlWarn,
+                    HintFmt(
+                        "Stack size hard limit is %1%, which is less than the desired %2%. If possible, increase the hard limit, e.g. with 'ulimit -Hs %3%'.",
+                        limit.rlim_max,
+                        stackSize,
+                        stackSize / 1024)
+                        .str());
+            }
+        }
+        auto requestedSize = std::min(static_cast<rlim_t>(stackSize), limit.rlim_max);
+        limit.rlim_cur = requestedSize;
         if (setrlimit(RLIMIT_STACK, &limit) != 0) {
             logger->log(
                 lvlError,
                 HintFmt(
-                    "Failed to increase stack size from %1% to %2% (maximum allowed stack size: %3%): %4%",
+                    "Failed to increase stack size from %1% to %2% (desired: %3%, maximum allowed: %4%): %5%",
                     savedStackSize,
+                    requestedSize,
                     stackSize,
                     limit.rlim_max,
                     std::strerror(errno))

src/nix/main.cc

@@ -584,7 +584,9 @@ int main(int argc, char ** argv)
 #ifndef _WIN32
     // Increase the default stack size for the evaluator and for
     // libstdc++'s std::regex.
-    nix::setStackSize(64 * 1024 * 1024);
+    // This used to be 64 MiB, but macOS as deployed on GitHub Actions has a
+    // hard limit slightly under that, so we round it down a bit.
+    nix::setStackSize(60 * 1024 * 1024);
 #endif
 
     return nix::handleExceptions(argv[0], [&]() { nix::mainWrapped(argc, argv); });

tests/functional/common/vars.sh

@@ -49,6 +49,9 @@ if ! isTestOnNixOS; then
   fi
   export _NIX_IN_TEST=$TEST_ROOT/shared
   export _NIX_TEST_NO_LSOF=1
+  # Suppress warnings that depend on the test environment (e.g., ulimit warnings)
+  # to avoid non-deterministic test failures in golden tests
+  export _NIX_TEST_NO_ENVIRONMENT_WARNINGS=1
   export NIX_REMOTE=${NIX_REMOTE_-}
 
 fi # ! isTestOnNixOS