Re: [cp-patches] Revise threading description in vmintegration.texinfo
Hi Ian, On Fri, 2006-08-18 at 16:42 +0100, Ian Rogers wrote: I'm resending this updated patch with a hope that someone will commit it now that I've got all the FSF paper work through. Finally I did this. Apologies for the huge delay. this patch revises the discussion of threading in the VM integration guide, as well as fixing a link to the Jikes RVM. A discussion was had on classpath@gnu.org on the 29/03/06 under the heading Green threads - some experience. The VM integration guide should now be up-to-date on this subject, although maybe my description of the problems is a little verbose. 2006-11-26 Ian Rogers [EMAIL PROTECTED] * doc/vmintegration.texinfo: Update VM Threading Model section. Committed, Mark signature.asc Description: This is a digitally signed message part
Re: [cp-patches] Revise threading description in vmintegration.texinfo
Hi,
I'm resending this updated patch with a hope that someone will commit it
now that I've got all the FSF paper work through.
Thanks,
Ian Rogers
Ian Rogers wrote:
Hi,
this patch revises the discussion of threading in the VM integration
guide, as well as fixing a link to the Jikes RVM. A discussion was had
on classpath@gnu.org on the 29/03/06 under the heading Green threads -
some experience. The VM integration guide should now be up-to-date on
this subject, although maybe my description of the problems is a little
verbose.
Regards,
Ian Rogers
-- http://www.cs.man.ac.uk/~irogers
Index: doc/vmintegration.texinfo
===
RCS file: /sources/classpath/classpath/doc/vmintegration.texinfo,v
retrieving revision 1.40
diff -u -r1.40 vmintegration.texinfo
--- doc/vmintegration.texinfo 22 Jul 2006 19:59:14 - 1.40
+++ doc/vmintegration.texinfo 18 Aug 2006 15:22:43 -
@@ -144,7 +144,7 @@
pure GNU Classpath; it is emerging as the preferred platform for
quickly testing a new build of GNU Classpath. Licensed under the GPL.
[EMAIL PROTECTED] @uref{http://oss.software.ibm.com/jikesrvm,Jikes RVM}
[EMAIL PROTECTED] @uref{http://jikesrvm.sourceforge.net/,Jikes RVM}
A free runtime environment for Java, written in Java. Works
out-of-the-box with pure GNU Classpath. Features an optimizing JIT.
Runs on the x86 and PowerPC architectures, on the AIX, Linux, and Mac
@@ -1859,8 +1859,7 @@
Classpath currently uses only JNI 1.1, except for one JNI 1.2 function
in the JNI Invocation API: GetEnv(). And GetEnv() is only used in the
-``portable native sync'' code, so it's only actually used by Jikes RVM
-and Kaffe.
+now deprecated ``portable native sync'' code.
A future direction will probably be to require that all VMs provide
JNI 1.2. If this poses problems, please raise them on the classpath
@@ -1870,42 +1869,95 @@
@comment node-name, next, previous, up
@section VM Threading Model
-Classpath's AWT peers use GTK+. GTK+ uses GLIB. Normally, Classpath
-will initialize GLIB's @dfn{gthreads} to use
-the platform's native threading [EMAIL PROTECTED] native threading
-model is pthreads on Linux and AIX, the two platforms Classpath
-currently runs on.}
-
-If the Java runtime doesn't use the native threading model, then you
-will want Classpath to tell GLIB to use the Java threading primitives
-instead. Otherwise, GLIB would use the native threading model to
-perform operations such as creating thread-local data, and that just
-doesn't work on systems (such as Kaffe in some configurations, and
-such as Jikes RVM) that use @i{m}:@i{n} threading.
-
-Historically, enabling the Java threading primitives had been done at
-build time, by configuring classpath with the
[EMAIL PROTECTED] option. This had bad consequences,
-though -- it meant that the prebuild GNU Classpath package distributed
-with Debian GNU/Linux would not be usable with VMs that could
-otherwise have used it. Instead, we encourage
-the use of the Java system property
[EMAIL PROTECTED] A VM that wants
-GLIB to use the Java threading primitives should modify
[EMAIL PROTECTED]()} to include code like the
-following:
-
[EMAIL PROTECTED]
-static void insertSystemProperties(Properties @var{p})
[EMAIL PROTECTED] example
-...
[EMAIL PROTECTED]
[EMAIL PROTECTED](gnu.classpath.awt.gtk.portable.native.sync, true);
[EMAIL PROTECTED] example
-
-So, the configure option
[EMAIL PROTECTED] is deprecated, and should go away in a
-subsequent release of GNU Classpath.
+VM authors can implement a number of different threading models. When
+native code is also threaded there is the potential for one threading
+model to deadlock the other. The
[EMAIL PROTECTED]://java.sun.com/docs/books/jni/html/other.html#29406,Java
+Native Interface Programmer's Guide and Specification} suggests
+consulting VM documentation in such situations. Classpath uses
+existing libraries, for example the AWT peers can use the GTK+
+graphics library. As these libraries assume a different threading
+model, there is the potential for the native code to deadlock a VM.
+
+The different threading models available to a VM author are:
[EMAIL PROTECTED]
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads}: Map a Java thread to an underlying operating system
+thread (normally a POSIX compatible pthread). This approach reduces
+the potential for deadlock as there is only one thread scheduling
+mechanism.
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads 1}: Green threads are threads scheduled by the VM,
+typically by switching swapping registers. In early VMs green threads
+were seen as advantageous as they didn't require the operating system
+to resechedule, save and swap all of a threads registers. The green
+thread 1 model switches thread on an externally created event, such as
+a timer interrupt. An example of a VM using this approach is Kaffe
+configured with its jthreads model.
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads 2}:
[cp-patches] Revise threading description in vmintegration.texinfo
Hi,
this patch revises the discussion of threading in the VM integration
guide, as well as fixing a link to the Jikes RVM. A discussion was had
on classpath@gnu.org on the 29/03/06 under the heading Green threads -
some experience. The VM integration guide should now be up-to-date on
this subject, although maybe my description of the problems is a little
verbose.
Regards,
Ian Rogers
-- http://www.cs.man.ac.uk/~irogers
Index: vmintegration.texinfo
===
RCS file: /sources/classpath/classpath/doc/vmintegration.texinfo,v
retrieving revision 1.27
diff -u -r1.27 vmintegration.texinfo
--- vmintegration.texinfo 17 Apr 2006 12:22:19 - 1.27
+++ vmintegration.texinfo 19 Apr 2006 10:56:55 -
@@ -143,7 +143,7 @@
pure GNU Classpath; it is emerging as the preferred platform for
quickly testing a new build of GNU Classpath. Licensed under the GPL.
[EMAIL PROTECTED] @uref{http://oss.software.ibm.com/jikesrvm,Jikes RVM}
[EMAIL PROTECTED] @uref{http://jikesrvm.sourceforge.net/,Jikes RVM}
A free runtime environment for Java, written in Java. Works
out-of-the-box with pure GNU Classpath. Features an optimizing JIT.
Runs on the x86 and PowerPC architectures, on the AIX, Linux, and Mac
@@ -1426,8 +1426,7 @@
Classpath currently uses only JNI 1.1, except for one JNI 1.2 function
in the JNI Invocation API: GetEnv(). And GetEnv() is only used in the
-``portable native sync'' code, so it's only actually used by Jikes RVM
-and Kaffe.
+now deprecated ``portable native sync'' code.
A future direction will probably be to require that all VMs provide
JNI 1.2. If this poses problems, please raise them on the classpath
@@ -1437,42 +1436,95 @@
@comment node-name, next, previous, up
@section VM Threading Model
-Classpath's AWT peers use GTK+. GTK+ uses GLIB. Normally, Classpath
-will initialize GLIB's @dfn{gthreads} to use
-the platform's native threading [EMAIL PROTECTED] native threading
-model is pthreads on Linux and AIX, the two platforms Classpath
-currently runs on.}
-
-If the Java runtime doesn't use the native threading model, then you
-will want Classpath to tell GLIB to use the Java threading primitives
-instead. Otherwise, GLIB would use the native threading model to
-perform operations such as creating thread-local data, and that just
-doesn't work on systems (such as Kaffe in some configurations, and
-such as Jikes RVM) that use @i{m}:@i{n} threading.
-
-Historically, enabling the Java threading primitives had been done at
-build time, by configuring classpath with the
[EMAIL PROTECTED] option. This had bad consequences,
-though -- it meant that the prebuild GNU Classpath package distributed
-with Debian GNU/Linux would not be usable with VMs that could
-otherwise have used it. Instead, we encourage
-the use of the Java system property
[EMAIL PROTECTED] A VM that wants
-GLIB to use the Java threading primitives should modify
[EMAIL PROTECTED]()} to include code like the
-following:
-
[EMAIL PROTECTED]
-static void insertSystemProperties(Properties @var{p})
[EMAIL PROTECTED] example
-...
[EMAIL PROTECTED]
[EMAIL PROTECTED](gnu.classpath.awt.gtk.portable.native.sync, true);
[EMAIL PROTECTED] example
-
-So, the configure option
[EMAIL PROTECTED] is deprecated, and should go away in a
-subsequent release of GNU Classpath.
+VM authors can implement a number of different threading models. When
+native code is also threaded there is the potential for one threading
+model to deadlock the other. The
[EMAIL PROTECTED]://java.sun.com/docs/books/jni/html/other.html#29406,Java
+Native Interface Programmer's Guide and Specification} suggests
+consulting VM documentation in such situations. Classpath uses
+existing libraries, for example the AWT peers can use the GTK+
+graphics library. As these libraries assume a different threading
+model, there is the potential for the native code to deadlock a VM.
+
+The different threading models available to a VM author are:
[EMAIL PROTECTED]
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads}: Map a Java thread to an underlying operating system
+thread (normally a POSIX compatible pthread). This approach reduces
+the potential for deadlock as there is only one thread scheduling
+mechanism.
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads 1}: Green threads are threads scheduled by the VM,
+typically by switching swapping registers. In early VMs green threads
+were seen as advantageous as they didn't require the operating system
+to resechedule, save and swap all of a threads registers. The green
+thread 1 model switches thread on an externally created event, such as
+a timer interrupt. An example of a VM using this approach is Kaffe
+configured with its jthreads model.
[EMAIL PROTECTED]
[EMAIL PROTECTED] threads 2}: The essential difference with this model is to
+not switch threads on an event, but at fixed points in the code being
+executed by the VM. Points chosen could be backward branches (loops)
