normal exit is not clean

[mavenlin]

A bug in luajit.
When executing the following,

torch.Tensor.__gc = function() print('gc') end
tensor = torch.Tensor(10)
-- tensor = nil
-- collectgarbage()

at exit 'gc' will not be printed, however when the last two lines of code are uncommented it will print 'gc'.
Which means at exit collectgarbage is not called by the interpreter.
It is a problem when gc writes log to files, or gc disconnects from a server.

@soumith What's your opinion on this?

[soumith]

@mavenlin it is interesting, and it is a bug in the trepl interpreter (not a bug in luajit).

For example, if you run the script with:
luajit [script.lua]
, you will see that it prints out "gc".
If you run the same with:
th [script.lua]
you dont see the print.

What's the use-case where you ran into this bug? It is likely something minor and not concerning to anything practically relevant.

[mavenlin]

@soumith In my case I wrapped the parameter server as userdata, gc calls the destructor in C++ side, which notifies the server side of the exit. If it is not gced the server is never notified.

[soumith]

fixed the issue via torch/trepl#38
Updating your trepl via: "luarocks install trepl" will solve the issue.
I'm updating distro to have this latest fix as well.

Thanks a lot for the report.