On Mon, 21 Mar 2022 15:28:17 +0100 Magnus Ihse Bursie wrote: > Hi, > > I'm working for Oracle on the OpenJDK build team. We're using GNU make > to build the JDK on all supported platforms. For Windows, we use Cygwin > as our build environment, including the Cygwin version of GNU make. > > We have had a long-standing issue with make losing jobserver tokens. > ("long-standing" here means for years, and years, at least since GNU > make 4.0, up to and including the current latest version in Cygwin.) > > Most runs end with something like: > > make[2]: INTERNAL: Exiting with 11 jobserver tokens available; should be > 12! > > Since the build still succeeds, and it just affects performance (and > typically not that much), we have not spend too much time getting to the > bottom of this. > > Now, however, I've come across a machine where this happens repeatedly, > and on a much worse scale: > > make[2]: INTERNAL: Exiting with 1 jobserver tokens available; should be 24! > > This effectively turns the highly parallelized builds into > single-threaded builds, and is absolutely detrimental for performance. > On the flip side, this also makes for the perfect testing environment to > really get to the bottom of this issue. > > I started out by sending a question to bug-m...@gnu.org. The folks over > there reported that this was not a known problem with GNU make on > Windows in general, and that as far as they knew, the mingw port did not > suffer from this problem. > > Instead, they suggested that it was a Cygwin-specific problem, possibly > related to issues with emulating Posix pipes and/or signals in Cygwin. > > So, my first question is: Is this a known problem in Cygwin GNU make? > Are there any workarounds/fixes to get around it? > > Otherwise: Any suggestions on how to go on and debug this? I am willing > to build and test an instrumented debug build of make, but I will need > assistance to find my way around the source and spot likely candidates > for the source of the problem.
I have tried to reproduce the issue by building OpenJDK from source, however, I could not. Instead, I encountered another issue. Building OpenJDK sometimes (rarely) failed with error such as: 0 [sig] make 5484 sig_send: error sending signal 11, pid 5484, pipe handle 0x118, nb 0, packsize 176, Win32 error 0 124917 [main] make 5484 sig_send: error sending signal -72, pid 5484, pipe handle 0x118, nb 0, packsize 176, Win32 error 0 common/modules/GensrcModuleInfo.gmk:77: *** open: /home/yano/jdk/build/windows-x86-server-release/make-support/vardeps/make/common/modules/GensrcModuleInfo.gmk/jdk.accessibility/ALL_MODULES.vardeps: No such file or directory. Stop. make[2]: *** [make/Main.gmk:141: jdk.accessibility-gensrc-moduleinfo] Error 2 make[2]: *** Waiting for unfinished jobs.... I looked into this new problem and found that wait_sig() thread crashes with segfault. It seems that accessing _main_tls causes access violation if a signal is sent just after the process is started. static void WINAPI wait_sig (VOID *) { [...] if (!pack.mask) { tl_entry = cygheap->find_tls (_main_tls); dummy_mask = _main_tls->sigmask; // <--- Segfault here cygheap->unlock_tls (tl_entry); pack.mask = &dummy_mask; } I also found the following patch resolves the issue. diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc index 62df96652..3824af199 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -1325,6 +1325,10 @@ wait_sig (VOID *) _sig_tls = &_my_tls; bool sig_held = false; + /* Wait for _main_tls initialization. */ + while (!cygwin_finished_initializing) + Sleep (10); + sigproc_printf ("entering ReadFile loop, my_readsig %p, my_sendsig %p", my_readsig, my_sendsig); I guess _main_tls may not be initialized correctly until cygwin_finished_initializing is set. Any comments would be appreciated. -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple