My apologies. I get python confused with perl. I know that python uses green threads. The link to libpthread.so proves that I was wrong.

ldd $(which perl)
    linux-vdso.so.1 =>  (0x00007fff22782000)
    libperl.so.5.18 => /usr/lib/libperl.so.5.18 (0x00007fd0faf9b000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fd0fabd5000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fd0fa9d0000
+)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fd0fa6ca000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f
+d0fa4ac000)
    libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007fd0fa
+272000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fd0fb345000)
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