RFR: 8257572: Deprecate the archaic signal-chaining interfaces: sigset and signal

[Erik Joelsson]

On Thu, 3 Dec 2020 04:34:52 GMT, David Holmes <dholmes at openjdk.org> wrote:

> The signal-chaining facility was introduced in JDK 1.4 nearly 20 years ago and supported three different Linux signal API's: sigset, signal and sigaction:
> 
> https://docs.oracle.com/javase/8/docs/technotes/guides/vm/signal-chaining.html
> 
> Only sigaction is a Posix supported API for multi-threaded processes, that we can use cross-platform. Both signal and sigset are obsolete and have undefined behaviour in a multi-threaded process. From the Linux man pages:
> 
> sigset: This API is obsolete: new applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.)
> 
> signal: The behavior of signal() varies across UNIX versions, and has also varied historically across different versions of Linux. Avoid its use: use sigaction(2) instead.
> 
> We should deprecate the use of signal and sigset in JDK 16 with a view to their removal in JDK 17.
> 
> A CSR request has been filed.
> 
> Testing: hotspot/jtreg/runtime/signal tests
> 
> Thanks,
> David

make/modules/java.base/Lib.gmk line 131:

> 129: ifeq ($(call isTargetOsType, unix), true)
> 130:   ifeq ($(STATIC_BUILD), false)
> 131:     LIBJSIG_CFLAGS += -DHOTSPOT_VM_DISTRO='"$(HOTSPOT_VM_DISTRO)"'

In general, I would prefer if a flag like this was just inlined in the SetupJdkLibrary call, as there are no complex conditionals for setting it. Looking a bit further, the variable LIBJSIG_CFLAGS is dead and not set anywhere in the build, so could also just be removed and replaced with your new -D flag.

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PR: https://git.openjdk.java.net/jdk/pull/1587