Date: Mon, 11 Feb 2019 12:15:06 +0000 From: Bob Bishop <rb@gid.co.uk> To: Banta Plan <bantaplan@outlook.de> Cc: "freebsd-toolchain@freebsd.org" <freebsd-toolchain@freebsd.org> Subject: Re: Problem with mutex.lock() Message-ID: <78296B5F-143C-4B4A-9D29-78AD81A1EE3E@gid.co.uk> In-Reply-To: <VI1PR02MB4671CBB16996C63C4ABB317BD7640@VI1PR02MB4671.eurprd02.prod.outlook.com> References: <VI1PR02MB4671CBB16996C63C4ABB317BD7640@VI1PR02MB4671.eurprd02.prod.outlook.com>
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Hi,
> On 11 Feb 2019, at 11:09, Banta Plan <bantaplan@outlook.de> wrote:
>=20
> I compiled this program and it crashes if executed.
>=20
> Compiled with: FreeBSD clang version 6.0.1 (tags/RELEASE_601/final =
335540) (based on LLVM 6.0.1)
>=20
> ## CMakeLists.txt
> cmake_minimum_required(VERSION 3.13)
> project(mainP)
>=20
> set(CMAKE_CXX_STANDARD 17)
>=20
> add_executable(mainP main.cpp)
>=20
> find_package(Threads)
> target_link_libraries(mainP ${CMAKE_THREAD_LIBS_INIT})
>=20
> ## main.cpp
>=20
> #include <iostream>
> #include <thread>
> #include <mutex>
> #include <chrono>
> #include <functional>
>=20
> int main() {
> using namespace std::chrono_literals;
> std::mutex m;
> m.lock();
[**]
> std::thread([&] {
> std::cout << "Before sleepFor" << std::endl;
> std::this_thread::sleep_for(2s);
>=20
> std::cout << "Before unlock" << std::endl;
> m.unlock();
> std::cout << "After unlock" << std::endl;
>=20
> }).detach();
> std::cout << "Before lock2" << std::endl;
> m.lock();
This lock is called by the main thread which already holds the lock [** =
above]. Apparently it doesn=E2=80=99t like that.
> std::cout << "After lock2" << std::endl;
>=20
> return 0;
> }
> ##
>=20
> This program compiles and runs under MacOS (Clang Version: Apple LLVM =
version 10.0.0 (clang-1000.11.45.5)) and
> manjaro arm64 with gcc (GCC) 8.2.1 20180831
>=20
>=20
>=20
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>=20
--
Bob Bishop t: +44 (0)118 940 1243
rb@gid.co.uk m: +44 (0)783 626 4518
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