Is lua-protobuf thread-safe / LuaLanes safe? about lua-protobuf

[starwing]

You could try compiling proto file to .pb file (using the official protoc executable and -o flag) first.

Then, try use protoc.new(), it doesn't need global state.

Thirdly, try pb.state(). Use separate state in one thread.

Other parts of lua-protobuf do not modify global state.

[ewmailing]

Thank you for the response. I am confused by the relationship of protoc and pb because the APIs never directly connect to each other (e.g. protoc doesn't return any parameters that you pass to pb functions).

If I compile a proto file to .pb (e.g. protoc --descriptor_set_out MyFoo.pb MyFoo.proto), does that let me avoid needing to use protoc?

	local fh, err = io.open("MyFoo.pb", "rb")
	local file_data = fh:read("*all")
	local pb = require("pb")
	pb.load(file_data)

Is this what you were suggesting with your first sentence?
Then I wouldn't need to use protoc at all, right? And so I wouldn't need protoc.new(), right?

FYI, each LuaLane creates a new lua_State to run in. So each pb probably gets its own state already, so I don't think I need pb.state() in my case.

Thank you

[starwing]

If I compile a proto file to .pb (e.g. protoc --descriptor_set_out MyFoo.pb MyFoo.proto), does that let me avoid needing to use protoc?

Yes.

Is this what you were suggesting with your first sentence?
Then I wouldn't need to use protoc at all, right? And so I wouldn't need protoc.new(), right?

Yes.

FYI, each LuaLane creates a new lua_State to run in. So each pb probably gets its own state already, so I don't think I need pb.state() in my case.

Okk, that make sense.

[ewmailing]

I haven't gotten any crashes since I made the change to load the .pb and avoid protoc. 👍

I'm just curious, what happens if I pb.load the same descriptor multiple times in the same state? Is this harmless? Is there a reloading cost or does the system know it is already loaded and returns early?

[ewmailing]

I spoke too soon. My crashes came back :(

I was looking at the source code in pb.c. There is a global variable called global_state:

lua-protobuf/pb.c

Line 131 in 449ad5d

static const pb_State *global_state = NULL;

My current hunch is that this may be related to my crashes while using Lanes. I'm thinking I want to try changing this to not use a global variable, to see if it will make my crashes go away. Can you give me any hints on what is involved to change this?

Thanks

[starwing]

this global just used in pb.state() routines, you could delete it (and relate codes) and see whether it works.

[ewmailing]

My crashes disappeared for a couple of weeks, but just came back.
I tried deleting global_state (and related code), but it didn't fix the problem. So that was a red herring for me.
So now, I think my problem might be caused by something unrelated (I hate threading bugs). But I think this part of lua-protobuf is fine and not the problem. Thanks for your help and time.