Hello,
I’m thinking to migrate my very own home
automation
tools from 5.1 to 5.3 …
One of the biggest problem I’m facing with
Lua is
multi-threading : all these tools are events driven,
especially, each and every MQTT message
arrival triggers a
new thread running some Lua code, and this is driven
from C side.
On 5.3 documentation, I can read
“Each Lua state
has one or more threads, which correspond to
independent,
cooperative lines of execution. The type lua_State (despite its name) refers to a thread.
(Indirectly, through the thread,
it also refers to the Lua state associated to the
thread.)” but cooperative looks to me it still not
real preemptive multi-threading
but still co-routines like, isn’t it ?
In my current application (using Lua 5.1),
I’m
creating new State for each thread but it create some
issues :
*
Global variables can’t be
used … but frankly speaking, it’s avoiding to deal with
concurrent access and I
created C side shared object for this which doing the
job pretty well.
*
More problematic : strings
comparison doesn’t work at all
If my_var == “toto”
Will
always fails. I got from this list it’s because there is
a lookup table to speed
up and this table is stick to the main State.
What would be the best solution to avoid
this 2nd
nasty issue ? Is implementing lua_(un)lock()still
the solution in 5.3 ? Does it mean I will have only a
single Lua_State shared
with all threads ?
Any better solution
Thanks
Laurent
