wendelin: Teach -dev build to dump all threads traceback on SIGUSR1

Via installing Products.signalstack

    https://pypi.python.org/pypi/Products.signalstack

/reviewed-by @Tyagov

software/wendelin/software-dev.cfg

@@ -7,7 +7,11 @@ parts -= wendelin.core
 parts += wendelin.core-dev
 
 
-# also tell erp5 to use -dev eggs instead of released ones
 [eggs]
+# tell erp5 to use -dev eggs instead of released ones
 eggs -= ${wendelin.core:egg}
 eggs += ${wendelin.core-dev:egg}
+
+# kill -USR1 <runzope-pid>    ->  traceback of all threads -> stdout
+#                                 ( logged to slappartX/.slappartX_zope-Y.log )
+        Products.signalstack

[Jérome Perrin]

FYI, ERP5 includes by default Products.DeadlockDebugger, so you can use:

curl http://10....:2200/manage_debug_threads?secret

to achieve more or less the same.

For now, you have to hit the backend Zope (not behind apache rewrite rule). The secret key is configured using deadlock-debugger-password parameter when requesting ERP5 instance.

[Jérome Perrin]

I just read description in https://pypi.python.org/pypi/Products.signalstack . I now understand there might be a good reason for including this :)

[Kirill Smelkov]

@jerome , yes - Products.signalstack uses just z3c.deadlockdebugger - the whole code of it is

import signal
import sys
from z3c.deadlockdebugger.threads import dump_threads


def showStacks(signal, stack):
    print dump_threads()
    sys.stdout.flush()


def initialize(contxt):
    signal.signal(signal.SIGUSR1, showStacks)

The thing here is that we can trigger the dump not only from web, but also via signal, e.g. when for some reason web request handling does not work.

---

If ERP5 includes Products.DeadlockDebugger by default, I think we could add Products.signalstack to be also available out of the box (you need access to slapos partition to send the signal, so it should be safe to enable)