Re: libssh multi-threading issue

[Anne Zhang <meantobe997@xxxxxxxxxxx>]

Hi Aris,

Thanks so much for the reply. It works in my Linux environment! I tried:

        static int initialized=0;
static pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_lock(&mutex1);
if (!initialized){
ssh_threads_set_callbacks(ssh_threads_get_pthread());
 ssh_init();
   initialized = 1;
}
pthread_mutex_unlock( &mutex1 );

So is there a similar mechanism in Windows? I noticed there is a
libssh_threads.so in libssh for linux but not for window.

 What do I pass in ssh_threads_set_callbacks() for windows? Is there
anything i should notice for the build of libssh under windows?


On Wed, Apr 16, 2014 at 11:43 AM, Dustin Oprea <myselfasunder@xxxxxxxxx>wrote:

> On Wed, Apr 16, 2014 at 2:26 PM, Aris Adamantiadis <aris@xxxxxxxxxxxx>wrote:
>
>> Hi Anne,
>>
>> There's an easy solution: before every ssh_connect, put an
>> initialization procedure protected by a mutex. This is not optimal
>> (because every new connection will have to lock+unlock a mutex) but you
>> are guaranteed that ssh_init gets called only once.
>>
>
> I like it. That's a cute solution for her requirements, Aris.
>
>
>
> Dustin
>
>
>> Pseudocode:
>>
>> do_my_connect(){
>> static int initialized=0;
>> static mutex init_mutex;
>>
>> mutex_lock(&init_mutex);
>> if (!initialized){
>>   initialize_threading();
>>   initialized = 1;
>> }
>> mutex_unlock(&init_mutex);
>>
>>
>> Regards,
>>
>> Aris
>>
>> Le 16/04/14 17:53, Anne Zhang a écrit :
>> > Hi Mike,
>> >
>> > Thanks for the reply. Unfortunately, I am only implementing an .so
>> > file and have no access to the main program. I understand ssh_init()
>> > would solve the problem but my library is being called within a thread
>> > and I cannot change what's in the main/original thread.
>> >
>> > Look forward to additional input.
>> >
>> > Thanks,
>> >
>> > Anne
>> >
>> >
>> > On Wed, Apr 16, 2014 at 2:53 AM, Mike Jones <mrjones@xxxxxxxxxx
>> > <mailto:mrjones@xxxxxxxxxx>> wrote:
>> >
>> >     On 4/16/2014 1:51 AM, ZhangAnne wrote:
>> >>     Hi,
>> >>
>> >>     I am implementing a shared library, and met the threading issue
>> >>     when the program calls my library and executes multiple threads
>> >>     in parallel. Since my lib is being called by other program, I
>> >>     cannot initialize the threading outside of any threading context
>> >>     as mentioned
>> >>     here: http://api.libssh.org/master/libssh_tutor_threads.html
>> >>
>> >>     My control to the code is limited within the scope of my library.
>> >>     I am wondering if there is any workaround other than changing
>> >>     code ouside my library?
>> >>
>> >>     Thanks,
>> >>
>> >>     Anne
>> >
>> >     If it helps, I used libssh in a multi-threaded application without
>> >     calling ssh_threads_set_callbacks() or linking libssh_threads.
>> >     In fact, I never even read this part of the libssh documentation
>> >     before today. :)
>> >
>> >     The main/original thread of the application calls ssh_init() and
>> >     then spawns off one additional thread that makes all the other
>> >     libssh calls.
>> >     The freeing of resources and ssh_finalize() are done back in the
>> >     original thread after this other thread has finished.
>> >
>> >     So far there have been no issues that I can attribute to using it
>> >     this way.
>> >
>> >     We're running on Linux (RedHat 6.x) and using libpthread.
>> >
>> >     - Mike
>> >
>> >
>> >
>> >
>>
>>
>>
>