Trac #9129: sqrt memory leaks

cf http://groups.google.com/group/sage-
support/browse_thread/thread/8c18b2b91004c35a#
{{{
m = get_memory_usage()
i=0
while True:
    i+=1
    a = 2.sqrt()
    if i%1000==0:
        print get_memory_usage(m)
}}}

URL: http://trac.sagemath.org/9129
Reported by: zimmerma
Ticket author(s): Volker Braun
Reviewer(s): Marc Mezzarobba

src/sage/symbolic/tests.py

@@ -0,0 +1,42 @@
+"""
+Tests for the Sage/Pynac interaction
+"""
+
+#*****************************************************************************
+#       Copyright (C) 2013 Volker Braun <vbraun.name@gmail.com>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#                  http://www.gnu.org/licenses/
+#*****************************************************************************
+
+
+def rational_powers_memleak():
+    """
+    Check that there is no memory leak in rational powers
+
+    OUTPUT:
+
+    Boolean. Whether the memory leak was detected.
+
+    See :trac:`9129`.
+
+    EXAMPLES::
+
+        sage: from sage.symbolic.tests import rational_powers_memleak
+        sage: rational_powers_memleak()
+        False
+    """
+    from sage.rings.all import ZZ
+    import gc
+    gc.collect()
+    c0 = sum(1 for obj in gc.get_objects())
+    for i in range(1000):
+        a = ZZ(2).sqrt()
+    gc.collect()
+    c1 = sum(1 for obj in gc.get_objects())
+    # Test that we do not leak an object at each iteration
+    return (c1 - c0) >= 1000
+