undefined reference to symbol 'pthread_key_delete##GLIBC_2.2.5 - linux

Question

I'm trying to make a file in Ubuntu and when i make i keep getting this error:
/usr/bin/ld: ../../gtest-1.7.0/libgtest.a(gtest-all.cc.o): undefined reference to symbol 'pthread_key_delete##GLIBC_2.2.5'
/lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make[2]: *** [src/tests/run_tests] Error 1
make[1]: *** [src/tests/CMakeFiles/run_tests.dir/all] Error 2
make: *** [all] Error 2
I saw someone mentioning to go into Makefile and adding '-L /lib64 -l pthread' to the variable LDFLAGS but how do you do that? Totally new to linux here =X

Answer 1

The above linking problem is solved by adding
-lpthread -lm to CMakeLists.txt (target link libraries for luxrender);
TARGET_LINK_LIBRARIES(... -lpthread -lm)

Answer 2

I hit the same issue: -lpthread should be last in your linking invocation
(has to do with mix of static and shared symbols)
So with CMake: ${CMAKE_THREAD_LIBS_INIT} should be last. For example:
target_link_libraries(mytestlib
${BINARY_DIR}/libgmock.a
glog
gflags
${Boost_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
And for the OP: Search for "thread" in the CMakeLists.txt for the project your are building and paste those section (or link which project you are trying to build if it is open source) - if the above isn't self explanatory

Answer 3

If you are building with Make or something else, add -pthread to the compilation command line (so GCC would generate thread-safe static locals) and to the linking command line (so GCC would tell the linker to do the right thing, most notably link with -lpthread).
If you are building with CMake - then most probably you need these (full example):
# always
FIND_PACKAGE(Threads REQUIRED)
# if using boost
SET(Boost_USE_MULTITHREADED ON)
TARGET_LINK_LIBRARIES(my_app ... ${CMAKE_THREAD_LIBS_INIT})