Memory Barriers at pthread using CYGWIN

Memory Barriers at pthread using CYGWIN

[Mümin A.]

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Hi,

I wrote a simple test for pthread_barrier_wait. it won't work as expected.

result should be

r1 = 1, r2 = 1

Thanks,
Mümin

[-- Attachment #2: CMakelists.txt --]
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cmake_minimum_required(VERSION 3.26)

project(test)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)


add_definitions(-D__POSIX_VISIBLE=200112 -D_POSIX_C_SOURCE=200112)

add_executable(test main.cpp)

target_link_libraries(test pthread)

[-- Attachment #3: main.cpp --]
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#include <stdio.h>
#include <pthread.h>

int x = 0;
int y = 0;
int r1 = 0;
int r2 = 0;

pthread_barrier_t barrier;

void* thread1(void* arg) {
    y = 1;
    pthread_barrier_wait(&barrier);  // Memory barrier
    r1 = x;
    return NULL;
}

void* thread2(void* arg) {
    x = 1;
    pthread_barrier_wait(&barrier);  // Memory barrier
    r2 = y;
    return NULL;
}

int main() {
    pthread_t t1, t2;

    pthread_barrier_init(&barrier, NULL, 2);

    pthread_create(&t1, NULL, thread1, NULL);
    pthread_create(&t2, NULL, thread2, NULL);

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);

    printf("r1 = %d, r2 = %d\n", r1, r2);

    pthread_barrier_destroy(&barrier);

    return 0;
}

RE: [EXTERNAL] Memory Barriers at pthread using CYGWIN

[Lavrentiev, Anton (NIH/NLM/NCBI) [C]]

> result should be
> 
> r1 = 1, r2 = 1
>

And what was the result you saw?

Anton Lavrentiev
Contractor NIH/NLM/NCBI

Re: [EXTERNAL] Memory Barriers at pthread using CYGWIN

[Mümin A.]

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r1=0 and r2=0
That is my result with Cygwin on windows. It’s false.

When I compiled with gcc. The result is correct but when I use lasted Cygwin gcc in windows 10. The result is false.


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________________________________
From: Lavrentiev, Anton (NIH/NLM/NCBI) [C] <lavr@ncbi.nlm.nih.gov>
Sent: Thursday, June 8, 2023 5:37:31 PM
To: Mümin A. <muminaydin06@gmail.com>; cygwin@cygwin.com <cygwin@cygwin.com>
Subject: RE: [EXTERNAL] Memory Barriers at pthread using CYGWIN

> result should be
>
> r1 = 1, r2 = 1
>

And what was the result you saw?

Anton Lavrentiev
Contractor NIH/NLM/NCBI

Re: [EXTERNAL] Memory Barriers at pthread using CYGWIN

[Kevin Schnitzius]

On Thursday, June 8, 2023 at 06:59:53 PM EDT, Mümin A. via Cygwin <cygwin@cygwin.com> wrote:

>
> r1=0 and r2=0
> That is my result with Cygwin on windows. It’s false.
> 
> When I compiled with gcc. The result is correct but when I use lasted Cygwin gcc in windows 10. The result is false.


> cmake .
CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
  CMake 3.26 or higher is required.  You are running version 3.25.3



> g++ main.cpp
>./a
r1 = 1, r2 = 1



Kevin

Re: Memory Barriers at pthread using CYGWIN

[Takashi Yano]

On Thu, 8 Jun 2023 22:58:59 +0000
Mümin A. wrote:
> r1=0 and r2=0
> That is my result with Cygwin on windows. It’s false.
> 
> When I compiled with gcc. The result is correct but when I use lasted Cygwin gcc in windows 10. The result is false.

I cannot reproduce your problem.

If I compile main.cpp with 'g++ main.cpp', a.exe outputs
r1 = 1, r2 = 1

If I use cmake, I get an error message:
CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
  CMake 3.26 or higher is required.  You are running version 3.25.3

My environment is:
cygwin 3.4.6
g++ (GCC) 11.4.0
cmake version 3.25.3

all packages are updated.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

Re: Memory Barriers at pthread using CYGWIN

[Duncan Roe]

On Thu, Jun 08, 2023 at 05:29:59PM +0300, cygwin wrote:
> Hi,
>
> I wrote a simple test for pthread_barrier_wait. it won't work as expected.
>
> result should be
>
> r1 = 1, r2 = 1
>
> Thanks,
> Mümin

> cmake_minimum_required(VERSION 3.26)
>
> project(test)
>
> set(CMAKE_CXX_STANDARD 14)
> set(CMAKE_CXX_STANDARD_REQUIRED ON)
> set(CMAKE_CXX_EXTENSIONS OFF)
>
>
> add_definitions(-D__POSIX_VISIBLE=200112 -D_POSIX_C_SOURCE=200112)
>
> add_executable(test main.cpp)
>
> target_link_libraries(test pthread)

> #include <stdio.h>
> #include <pthread.h>
>
> int x = 0;
> int y = 0;
> int r1 = 0;
> int r2 = 0;
>
> pthread_barrier_t barrier;
>
> void* thread1(void* arg) {
>     y = 1;
>     pthread_barrier_wait(&barrier);  // Memory barrier
>     r1 = x;
>     return NULL;
> }
>
> void* thread2(void* arg) {
>     x = 1;
>     pthread_barrier_wait(&barrier);  // Memory barrier
>     r2 = y;
>     return NULL;
> }
>
> int main() {
>     pthread_t t1, t2;
>
>     pthread_barrier_init(&barrier, NULL, 2);
>
>     pthread_create(&t1, NULL, thread1, NULL);
>     pthread_create(&t2, NULL, thread2, NULL);
>
>     pthread_join(t1, NULL);
>     pthread_join(t2, NULL);
>
>     printf("r1 = %d, r2 = %d\n", r1, r2);
>
>     pthread_barrier_destroy(&barrier);
>
>     return 0;
> }

WFFM (compiled as a C program)

Cheers ... Duncan.