watchdog for gevent greenlets

example.py

# Small snippet that shows how to put a watchdog around a greenlet.                                                                                                             
# When the watchdog is triggered, a stacktrace of the greenlet is                                                                                                               
# printed.                                                                                                                                                                      

import gevent
import traceback
import sys


def a(a=10):
    c = 20
    gevent.sleep(5)

def b(d):
    x = d + 10
    a(x)

def c():
    b(20)

def dogslow(g, timeout=1):
    try:
        return g.get(True, timeout=timeout)
    except gevent.Timeout:
        print >>sys.stderr, "Watchdog triggered:"
        sys.stderr.write(''.join(traceback.format_stack(g.gr_frame)))

dogslow(gevent.spawn(c))

monitor.py

def monitor(g, timeout=1):
    """Puts a watchdog around greenlet `g`.  If the greenlet                                                                                                                    
    has not finished within `timeout` seconds, take a traceback                                                                                                                 
    and wait for the greenlet to finish.                                                                                                                                        
    """
    t0 = time.time()
    try:
        return g.get(True, timeout=timeout)
    except gevent.Timeout:
        tb = traceback.format_stack(g.gr_frame)
        try:
            return g.get(True)
        finally:
            print >>sys.stderr, "Operation took %.3f seconds, expected max %.3f" % (
                time.time() - t0, timeout)
            print >>sys.stderr, "Traceback at %.3f into the operation:" % (timeout,)
            sys.stderr.write(''.join(tb))