Throttle garbage collector frequency in sig_occurred

src/cysignals/signals.pxd

@@ -29,6 +29,7 @@ cdef extern from "struct_signals.h":
         cy_atomic_int block_sigint
         const char* s
         PyObject* exc_value
+        double gc_pause_until
 
 
 cdef extern from "macros.h" nogil:

src/cysignals/signals.pyx

@@ -29,6 +29,7 @@ from cpython.ref cimport Py_XINCREF, Py_CLEAR
 from cpython.exc cimport (PyErr_Occurred, PyErr_NormalizeException,
         PyErr_Fetch, PyErr_Restore)
 from cpython.version cimport PY_MAJOR_VERSION
+import time
 
 cimport cython
 import sys
@@ -396,14 +397,19 @@ cdef void verify_exc_value() noexcept:
             Py_CLEAR(cysigs.exc_value)
             return
 
-    # To be safe, we run the garbage collector because it may clear
-    # references to our exception.
-    try:
-        collect()
-    except Exception:
-        # This can happen when Python is shutting down and the gc module
-        # is not functional anymore.
-        pass
+    cdef double cur_time = time.perf_counter(), finish_time
+    if cysigs.gc_pause_until == 0 or cysigs.gc_pause_until < cur_time:
+        # To be safe, we run the garbage collector because it may clear
+        # references to our exception.
+        try:
+            collect()
+        except Exception:
+            # This can happen when Python is shutting down and the gc module
+            # is not functional anymore.
+            pass
+
+        finish_time = time.perf_counter()
+        cysigs.gc_pause_until = finish_time + (finish_time - cur_time) * 5
 
     # Make sure we still have cysigs.exc_value at all; if this function was
     # called again during garbage collection it might have already been set

src/cysignals/struct_signals.h

@@ -26,6 +26,7 @@
 #include <setjmp.h>
 #include <signal.h>
 #include <Python.h>
+#include <sys/time.h>
 
 
 /* Choose sigjmp/longjmp variant */
@@ -92,6 +93,10 @@ typedef struct
      * This is used by the sig_occurred function. */
     PyObject* exc_value;
 
+    /* Time until calling garbage collector is allowed. Using Python time.perf_counter.
+     * See https://github.com/sagemath/cysignals/issues/215. */
+    double gc_pause_until;
+
 #if ENABLE_DEBUG_CYSIGNALS
     int debug_level;
 #endif

src/cysignals/tests.pyx

@@ -933,6 +933,8 @@ def test_sig_occurred_finally():
     """
     TESTS::
 
+        >>> from time import sleep
+        >>> sleep(0.5)  # see PR 227
         >>> from cysignals.tests import *
         >>> test_sig_occurred_finally()
         No current exception
@@ -1022,6 +1024,8 @@ def test_sig_occurred_dealloc_in_gc():
         >>> l = [DeallocDebug(), e]
         >>> l.append(l)
         >>> gc.disable()
+        >>> from time import sleep
+        >>> sleep(0.5)  # see PR 227
         >>> try:
         ...     del l, e
         ...     print_sig_occurred()