From: jiangsh92@... Date: 2020-04-23T06:16:16+00:00 Subject: [ruby-core:98025] [Ruby master Bug#16808] Thread#name= only accepts up to 15 characters with Linux/pthread implementation Issue #16808 has been reported by jiasha (Shan Jiang). ---------------------------------------- Bug #16808: Thread#name= only accepts up to 15 characters with Linux/pthread implementation https://bugs.ruby-lang.org/issues/16808 * Author: jiasha (Shan Jiang) * Status: Open * Priority: Normal * ruby -v: 2.7.1 * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- Repro: irb(main):001:0> RUBY_VERSION => "2.7.1" irb(main):002:0> Thread.new { Thread.current.name = 'abcdefg'; sleep } => # irb(main):003:0> Thread.new { Thread.current.name = 'abcdefghijklmnopqrst'; sleep } => # irb(main):004:0> Thread.new { Thread.current.name = 'abcdefghijklmnop'; sleep } => # irb(main):005:0> Thread.new { Thread.current.name = 'abcdefghijklmno'; sleep } => # Result: $ ps -T -p PID PID SPID TTY TIME CMD 13137 13137 pts/0 00:00:00 irb 13137 13158 pts/0 00:00:00 abcdefg 13137 13160 pts/0 00:00:00 (irb):3 13137 13165 pts/0 00:00:00 (irb):4 13137 13167 pts/0 00:00:00 abcdefghijklmno It looked like the Linux implementation calls pthread_setname_np(), which limits the length of thread names to 15 characters, which is a hardcoded constant (TASK_COMM_LEN) in the kernel: https://code.woboq.org/userspace/glibc/sysdeps/unix/sysv/linux/pthread_setname.c.html#pthread_setname_np Thread#name= calls pthread_setname_np() without checking its return value: https://github.com/ruby/ruby/blob/0256e4f0f5e10f0a15cbba2cd64e252dfa864e4a/thread_pthread.c#L1615 Since it's unlikely for one to call this method intensely, fetch/checking the thread name again after setting it, or even truncating the passed in string to 15 characters in this method might be a better solution. -- https://bugs.ruby-lang.org/ Unsubscribe: