I have a web application, which runs several subprocesses to build a page.
This runs pretty well with subprocess.check_output(…).
To improve concurrency with other web sessions, I’m converting this to
ireactorprocess.spawnProcess with inline callbacks:
—-
class SubprocessProtocol(ProcessProtocol):
outBuffer = ""
errBuffer = ""
def connectionMade(self):
self.d = Deferred()
def outReceived(self, data):
self.outBuffer += data
def errReceived(self, data):
self.errBuffer += data
def processEnded(self, reason):
if reason.check(ProcessDone):
self.d.callback(self.outBuffer)
else:
self.d.errback(reason)
def subprocess(args, ireactorprocess=None):
"""
:type args: list of str
:type ireactorprocess: :class: twisted.internet.interfaces.IReactorProcess
:rtype: Deferred
"""
deblog('Running ' + str(args))
if ireactorprocess is None:
from twisted.internet import reactor
ireactorprocess = reactor
pprotocol = SubprocessProtocol()
ireactorprocess.spawnProcess(pprotocol, args[0], args)
return protocoled
—-
I have chained up the calls to subprocess with the expectation, that they will
be called sequentially one after the previous has been finished:
—-
def render_GET(self, request):
...
self.A()
return NOT_DONE_YET
@inlineCallbacks
def A(self):
...
tmp = yield subprocess(args)
...
self.B()
@inlineCallbacks
def B(self):
...
tmp = yield subprocess(args)
...
self.C()
def C(self):
...
x = self.D(...)
y = self.D(...)
z = self.D(...)
...
self.E()
@inlineCallbacks
def D(self):
...
tmp = yield subprocess(args)
...
returnValue(tmp)
@inlineCallbacks
def E(self):
...
tmp = yield subprocess(args)
...
request.write(...)
request.finished
—-
In C, the three calls to self.D run in parallel.
How can I serialize this?
Thanks, Axel
---
PGP-Key:29E99DD6 ☀ +49 151 2300 9283 ☀ computing @ chaos claudius
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