Question: Is there a performance related reason why Twisted core does not use inlineCallbacks? ----- I'm trying to figure out how to reduce the CPU load of an app. I've already done a lot of profiling and have trimmed a lot of fat, but we're still not getting as much throughput as we'd like. We don't seem to really be I/O bound in our application, but mostly CPU bound. One thing we use a lot in our code is the inlineCallbacks decorator. It's also used by txAMQP, at least in the 0.2 version we are currently using. However, I notice it doesn't seem to really be used anywhere in the Twisted core code; I only see its definition and the defgen test which uses it. I'm curious of the reason why Twisted core does not use it. Is it performance related? Compatibility with older Python versions? Or something else? Thanks. - Paul Goins ---- For those curious, here's what I'm currently facing: If I count total "internal time" per module (NOT cumulative time), the current hotspot is twisted.internet.defer with 27.88% of all CPU time. The per-function breakdown is something like this: ======================= ===================== Line(Function) Time (total time pct) ======================= ===================== 314(_runCallbacks) 7.657 733(_inlineCallbacks) 6.246 833(unwindGenerator) 2.864 172(addCallbacks) 2.103 291(_startRunCallbacks) 1.940 206(addBoth) 1.369 766(gotResult) 1.165 233(callback) 1.014 ======================= ===================== Twisted version: 8.2.0. Profiler: cProfile. I'm trying to find the best way of getting this down. It seems like reducing the raw number of callbacks is probably the best way if possible. However, unwindGenerator/_inlineCallbacks by itself takes almost 10% of the time... hence the above question.