/usr/bin/ld: cannot find -lpthreads

Question

I'm compiling NVIDIA Caffe tool on a Fedora 22 and I having problems to find lpthread library:

Determining if the pthread_create exist failed with the following output:
Change Dir: /home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_d410e/fast"
/usr/bin/gmake -f CMakeFiles/cmTC_d410e.dir/build.make CMakeFiles/cmTC_d410e.dir/build
gmake[1]: Entering directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_d410e.dir/CheckSymbolExists.c.o
/usr/bin/cc    -o CMakeFiles/cmTC_d410e.dir/CheckSymbolExists.c.o   -c /home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_d410e
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_d410e.dir/link.txt --verbose=1
/usr/bin/cc       CMakeFiles/cmTC_d410e.dir/CheckSymbolExists.c.o  -o cmTC_d410e -rdynamic 
CMakeFiles/cmTC_d410e.dir/CheckSymbolExists.c.o: En la función `main':
CheckSymbolExists.c:(.text+0x16): referencia a `pthread_create' sin definir
collect2: error: ld devolvió el estado de salida 1
CMakeFiles/cmTC_d410e.dir/build.make:97: recipe for target 'cmTC_d410e' failed
gmake[1]: Leaving directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_d410e/fast' failed
gmake[1]: *** [cmTC_d410e] Error 1
gmake: *** [cmTC_d410e/fast] Error 2

File /home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_create
  return ((int*)(&pthread_create))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_e693b/fast"
/usr/bin/gmake -f CMakeFiles/cmTC_e693b.dir/build.make CMakeFiles/cmTC_e693b.dir/build
gmake[1]: Entering directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_e693b.dir/CheckFunctionExists.c.o
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_e693b.dir/CheckFunctionExists.c.o   -c /usr/share/cmake/Modules/CheckFunctionExists.c
Linking C executable cmTC_e693b
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_e693b.dir/link.txt --verbose=1
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTC_e693b.dir/CheckFunctionExists.c.o  -o cmTC_e693b -rdynamic -lpthreads 
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld outputs 1
CMakeFiles/cmTC_e693b.dir/build.make:97: recipe for target 'cmTC_e693b' failed
gmake[1]: Leaving directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_e693b/fast' failed
gmake[1]: *** [cmTC_e693b] Error 1
gmake: *** [cmTC_e693b/fast] Error 2

It seems that it doesn't find pthreads lib (/usr/bin/ld: cannot find -lpthreads), but running command find / name "*pthread*" it outputs this:

/usr/lib64/libpthread.so
/usr/lib64/libpthread.a
/usr/lib64/libpthread_nonshared.a
/usr/lib64/libpthread-2.21.so
/usr/lib64/libpthread.so.0

But there is something strange with this, becaue CMakeOutut.log has this: Determining if the function pthread_create exists in the pthread passed with the following output:

Change Dir: /home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_705ba/fast"
/usr/bin/gmake -f CMakeFiles/cmTC_705ba.dir/build.make CMakeFiles/cmTC_705ba.dir/build
gmake[1]: Entering directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_705ba.dir/CheckFunctionExists.c.o
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_705ba.dir/CheckFunctionExists.c.o   -c /usr/share/cmake/Modules/CheckFunctionExists.c
Linking C executable cmTC_705ba
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_705ba.dir/link.txt --verbose=1
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTC_705ba.dir/CheckFunctionExists.c.o  -o cmTC_705ba -rdynamic -lpthread 
gmake[1]: Leaving directory '/home/user1/Sources/caffe/build/CMakeFiles/CMakeTmp'

It has this line using lpthread:

/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTC_705ba.dir/CheckFunctionExists.c.o  -o cmTC_705ba -rdynamic -lpthread

And this is CMakeList.txt:

cmake_minimum_required(VERSION 2.8.7)

# ---[ Caffe project
project(Caffe C CXX)

# ---[ Caffe version
set(CAFFE_TARGET_VERSION "0.14.5")
set(CAFFE_TARGET_SOVERSION "0.14")
add_definitions(-DCAFFE_VERSION=${CAFFE_TARGET_VERSION})

# ---[ Using cmake scripts and modules
list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake/Modules)

include(ExternalProject)

include(cmake/Utils.cmake)
include(cmake/Targets.cmake)
include(cmake/Misc.cmake)
include(cmake/Summary.cmake)
include(cmake/ConfigGen.cmake)

# ---[ Options
caffe_option(CPU_ONLY  "Build Caffe without CUDA support" OFF) # TODO: rename to USE_CUDA
caffe_option(USE_CUDNN "Build Caffe with cuDNN library support" ON IF NOT CPU_ONLY)
caffe_option(BUILD_SHARED_LIBS "Build shared libraries" ON)
caffe_option(BUILD_python "Build Python wrapper" ON)
set(python_version "2" CACHE STRING "Specify which Python version to use")
caffe_option(BUILD_matlab "Build Matlab wrapper" OFF IF UNIX OR APPLE)
caffe_option(BUILD_docs   "Build documentation" ON IF UNIX OR APPLE)
caffe_option(BUILD_python_layer "Build the Caffe Python layer" ON)
caffe_option(USE_OPENCV "Build with OpenCV support" ON)
caffe_option(USE_LEVELDB "Build with levelDB" ON)
caffe_option(USE_LMDB "Build with lmdb" ON)
caffe_option(ALLOW_LMDB_NOLOCK "Allow MDB_NOLOCK when reading LMDB files (only if necessary)" OFF)

# ---[ Dependencies
include(cmake/Dependencies.cmake)

# ---[ Flags
if(UNIX OR APPLE)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -Wall")
endif()

if(USE_libstdcpp)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libstdc++")
  message("-- Warning: forcing libstdc++ (controlled by USE_libstdcpp option in cmake)")
endif()

add_definitions(-DGTEST_USE_OWN_TR1_TUPLE)

# ---[ Warnings
caffe_warnings_disable(CMAKE_CXX_FLAGS -Wno-sign-compare -Wno-uninitialized)

# ---[ Config generation
configure_file(cmake/Templates/caffe_config.h.in "${PROJECT_BINARY_DIR}/caffe_config.h")

# ---[ Includes
set(Caffe_INCLUDE_DIR ${PROJECT_SOURCE_DIR}/include)
set(THIRDPARTY_DIR ${PROJECT_SOURCE_DIR}/3rdparty)
include_directories(${Caffe_INCLUDE_DIR} ${PROJECT_BINARY_DIR} ${THIRDPARTY_DIR})
include_directories(BEFORE src) # This is needed for gtest.

# ---[ Subdirectories
add_subdirectory(src/gtest)
add_subdirectory(src/caffe)
add_subdirectory(tools)
add_subdirectory(examples)
add_subdirectory(python)
add_subdirectory(matlab)
add_subdirectory(docs)

# ---[ Linter target
add_custom_target(lint COMMAND ${CMAKE_COMMAND} -P ${PROJECT_SOURCE_DIR}/cmake/lint.cmake)

# ---[ pytest target
add_custom_target(pytest COMMAND python${python_version} -m unittest discover -s caffe/test WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/python )
add_dependencies(pytest pycaffe)

# ---[ Configuration summary
caffe_print_configuration_summary()

# ---[ Export configs generation
caffe_generate_export_configs()

What do I have to install? Does libphreads exist or I have to use libphread?

Solution

You have a typo. You should use -lpthread instead of -lpthreads.

Alternatively you can just use -pthread, that also works.

Comments

[VansFannel]

Maybe Caffe has a typo. I'm only running cmake ..

[Smeeheey]

Then you should share your cmake config file. Somewhere therein there will be an incorrect definition of the pthread switch value

[Smeeheey]

It'll most likely be called CMakeLists or CMakeLists.txt

[VansFannel]

I have updated my question with the contents of CMakeLists.txt.

[Matt Schuchard]

I just did a search on pthreads in the nvidia/caffe project and nothing was found in the current commit. Sounds like a reclone would fix the typo.