SEGFAULT calling lua #84
Comments
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I know it can be hard, but could you try creating a small-ish reproducible example? |
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I have really tried boiling this down to a simple example to reproduce this issue. I am not sure I have succeded but in the mean time I have been able to reproduce a similar segfault. Not sure if this is the same issue. |
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I think I have some more information. I think the cause is two different threads try to access the lua runtime. The above example does this intentionally but in my software this is a side effect. Let me try to explain. I have not managed to create an isolated example of this but it is fairly reproducible in my project. Here is an example of the wrapper object: The segfault happens even without the destructor. I added the destructor with an implicit "freeing" of |
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Backtrace of the above observations: |
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Finally, a small-ish reproducible example! No threads or anything special... ;) |
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Did you do any more work on this? I'm new to lua, but have done my share of python.. can i help? |
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I can only answer from my side. I have tried to see where the crash happen but I could not understand fully why. |
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I can reproduce the crash, but the stack trace changes on each run. That suggests that there might be some kind of Lua stack corruption that only shows at a later point. Meaning, the crash is almost certainly not where the problem is. |
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Able to reproduce using Going to test a couple of versions now |
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Well, it's certainly worth git bisect-ing it, although my intuition wants me to assume that it's been there forever, or at least as long as the features that the reproducer script uses are around...
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Tried a couple of random versions..
all crashes randomly between 15 and 400.. |
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Running the test and just watching it fail, dumps a lot of different errors on the console. Mostly segfaults, but also python malloc ( This might be a stupid question, but if I move |
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Maybe you could try to strip down the test case? It's very complex and uses lots of features: Lua couroutines, the |
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I'm very new to lua, so I'm not sure where to begin... I'll continue playing with it a little tho.. |
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Another strange find is that if I set anything under Example.. is the original.. does not crash... But do crash.. |
I have simplified the test case. Actually, removing the runtime options makes the script crash sooner on my machine. Two observations:
Maybe this has something to do when the |
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I tried to turn off gc. |
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Has there been any work done on this? I'm running into the same issue with coroutines unpredictably segfaulting. |
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From my side, no, unfortunately not. |
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There is a reproducing script in https://gist.github.com/mickeprag/75a0fbf04cfd06c3fe48b759da22f5ef |
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Here's a slightly more minimal reproducing script: from lupa import LuaRuntime
class PendingRequest:
def __init__(self, callback):
self.callback = callback
def make_request(callback):
return PendingRequest(callback)
lua = LuaRuntime()
lua.globals().make_request = make_request
run = lua.eval("""
function()
make_request(function() end)
end
""")
for i in range(10000):
print("Start call", i)
thread = run.coroutine()
try:
thread.send(None)
except StopIteration:
pass
print("Finished successfully")Almost every time I run this I get an error similar to this: So I do think it's likely there is some error with garbage collection/deallocation. I'm still not so comfortable debugging Cython but I'll try to look at this more over the weekend. |
I am getting segfaults from time to time. It seems to happen when python objects are wrapped and sent to the lua runtime.
Lupa version 1.4
Lua: tested version 5.1.5, 5.2.3, and luajit 2.0.4
Backtraces of the crash:
Lua:
Luajit:
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