Some thread/GC questions

[Daniel Kochmański]

Hello,

Juraj Variny writes:

> Hello,
>
> can you please tell me how to:
>
> 1. Initialize lisp environment in a thread that was already created by C/C++ 
> app? Is it possible for it to share existing lisp environment?

There is an example in examples/embed directory (file hello.c). What do
you mean by sharing an existing lisp environment? cl_boot creates an
environment for this instance.
>
> 2. Is accessing and modification of the shared lisp environment from a new 
> thread made by (mp:process-run-function) threadsafe? For example I am running 
> swank this way, is this a safe practice?

It is meant to be. Any reproducible bug should be reported here:
https://gitlab.com/embeddable-common-lisp/ecl/issues/ . I'm using swank
from the separate thread in ecl-android and I didn't encounter problems
with that.

ECL's swank backend contains in comment some hint regarding the thread
safety (not sure though, how up-to-date it is):

  ;; While ECL does provide threads, some parts of it are not
  ;; thread-safe (2010-02-23), including the compiler and CLOS.

it is something I want to investigate. I'm currently working on
something else in the compiler though.
>
> 3. In the environment where only ECL is garbage collected: Calling 
> ecl_base_string_pointer_safe(si_copy_to_simple_base_string(obj)) means that 
> resulting C string will be eventually garbage collected?

Yes.
>
> 4. Likewise (ffi:c-inline () () :cstring "...") returns the value via 
> ecl_cstring_to_base_string_or_nil() which causes trouble when C side 
> deallocates it, I presume?

Yes.
>
> Regards,
>
> Juraj

Best reagrds,
Daniel

-- 
Daniel Kochmański ;; aka jackdaniel | Poznań, Poland
TurtleWare - Daniel Kochmański      | www.turtleware.eu

"Be the change that you wish to see in the world." - Mahatma Gandhi