Previously, we waited until the next GC to do this, but that can be
too long for workloads which create a lot of short-lived threads but
don't do much allocation.
The first bug affected POSIX systems: if the app never called
Process.waitFor, we'd never call waitpid on the child and thus leak a
zombie process. This patch ensures that we always call waitpid by
spawning a thread to handle it.
The second bug affected Windows systems: we weren't closing the
child's ends of the stdin, stdout, and stderr pipes after process
creation, which lead to us blocking forever while reading from the
child's stdout or stderr.
This requires adding LinkRegister to the list of reserved registers,
since it must be preserved in the thunk code generated by
compileDirectInvoke. An alternative would be to explicitly preserve
it in that special case, but that would complicate the code quite a
bit.
All the tests are passing for openjdk-src builds, but the non-src
openjdk build is crashing and there's trouble loading time zone info
from the embedded java.home directory.
This allows OpenJDK to access time zone data which is normally found
under java.home, but which we must embed in the executable itself to
create a self-contained build. The VM intercepts various file
operations, looking for paths which start with a prefix specified by
the avian.embed.prefix property and redirecting those operations to an
embedded JAR.
For example, if avian.embed.prefix is "/avian-embedded", and code
calls File.exists() with a path of
"/avian-embedded/javahomeJar/foo.txt", the VM looks for a function
named javahomeJar via dlsym, calls the function to find the memory
region containing the embeded JAR, and finally consults the JAR to see
if the file "foo.txt" exists.
sun.misc.Unsafe.getUnsafe expects a null result if the class loader is
the boot classloader and will throw a SecurityException otherwise
(whereas it should really be checking both for null and comparing
against the system classloader). However, just returning null
whenever the loader is the boot loader can cause trouble for embedded
apps which put everything in the boot loader, including application
resources.
Therefore, we only return null if it's the boot loader and we're being
called from Unsafe.getUnsafe.
As described in readme.txt, a standalone OpenJDK build embeds all
libraries, classes, and other files needed at runtime in the resulting
binary, eliminating dependencies on external resources.
Consider the following makefile construct:
target: dep0
target: dep1 dep2
command -o $(@) $(^)
With some versions of make, $(^) will expand to "dep1 dep2", but on
others it will expand to "dep0 dep1 dep2". The commit ensures that we
no longer rely on the former behavior (nor the latter, for that matter).
Due to a silly cut-and-paste error, we were incorrectly passing the
stdout and stderr file descriptors back from native code to Java,
which prevented reading the output of the child process.
Rather than try to support mixing Avian's core classes with those of
an external class library -- which necessitates adding a lot of stub
methods which throw UnsupportedOperationExceptions, among other
comprimises -- we're looking to support such external class libraries
in their unmodified forms. The latter strategy has already proven
successful with OpenJDK's class library. Thus, this commit removes
the stub methods, etc., which not only cleans up the code but avoids
misleading application developers as to what classes and methods
Avian's built-in class library supports.
