g++ -std=c++17 -I ../../include/ ../thread-pool.cpp ../workerpool.cpp test.cpp ../thread-key.cpp ../../common/identity-pool.cpp x.cpp ../../common/alog.cpp -D_POSIX_C_SOURCE -O2 -DTEST

note that:
1. -std=c++17 is required (but I don't konw why);
2. -D_POSIX_C_SOURCE is required for alog.cpp to use gmtime_r();
3. -DTEST is required for x.cpp to provide mocks of photon::init() and photon::fini();
x

in thread/test/
g++ -std=c++17 -I ../../include/ -DThreadUT test.cpp x.cpp ../thread-pool.cpp ../workerpool.cpp ../thread-key.cpp ../../common/identity-pool.cpp ../../common/alog.cpp -lgtest -lgflags -O2