tools/tests/heartbeat/gilsleep.ipynb

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    "Holding the GIL for too long could disrupt the heartbeat due to non-copying sends.\n",
    "\n",
    "The following cell repeatedly calls a function that holds the GIL for five seconds.\n",
    "\n",
    "The heartbeat will fail after a few iterations prior to fixing Issue [#1260](https://github.com/ipython/ipython/issues/1260)."
   ]
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    "import sys\n",
    "import time\n",
    "\n",
    "from cython import inline\n",
    "\n",
    "def gilsleep(t):\n",
    "    \"\"\"gil-holding sleep with cython.inline\"\"\"\n",
    "    code = '\\n'.join([\n",
    "        'from posix cimport unistd',\n",
    "        'unistd.sleep(t)',\n",
    "    ])\n",
    "    while True:\n",
    "        inline(code, quiet=True, t=t)\n",
    "        print time.time()\n",
    "        sys.stdout.flush() # this is important\n",
    "\n",
    "gilsleep(5)"
   ]
  },
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