RFR: JDK-8167195: VM fails to initialize intermittently when running jmod to create some images

[Erik Joelsson]

Hello,

Please review this small patch, which should fix an issue introduced by 
JDK-8166948. At least on Windows, running jmod on the exploded image may 
fail if the new optimization target is running concurrently. I had 
missed adjusting the dependencies for the jmod targets.

Bug: https://bugs.openjdk.java.net/browse/JDK-8167195

Patch:

diff -r 4bd1866d819b make/Main.gmk
--- a/make/Main.gmk
+++ b/make/Main.gmk
@@ -615,15 +615,19 @@
    $(foreach m, $(LAUNCHER_MODULES), $(eval $m-jmod: $m-launchers))
    $(foreach m, $(COPY_MODULES), $(eval $m-jmod: $m-copy))

-  # Jmods cannot be created until we have the jlink tool ready to run, 
which requires
-  # all java modules to be compiled and jdk.jlink-launchers.
-  # And we also need to copy jvm.cfg (done in java.base-copy) and 
tzdb.dat (done in
-  # java.base-gendata) to the appropriate location otherwise jimage, 
jlink and jmod won't start.
+  # Jmods cannot be created until we have the jlink tool ready to run. 
During
+  # the build we run it from the exploded image. To be runnable, all java
+  # modules and jdk.jlink-launchers need to be built. We also need to copy
+  # jvm.cfg (done in java.base-copy) and tzdb.dat (done in 
java.base-gendata)
+  # to the appropriate location otherwise jimage, jlink and jmod won't 
start.
    $(JMOD_TARGETS): java.base-libs java.base-copy java.base-gendata 
jdk.jlink-launchers
-  # When creating a BUILDJDK, the java compilation has already been 
done by the
-  # normal build and copied in.
+  # The above is enough when creating a BUILDJDK since the java modules 
have
+  # been compiled by the normal build and copied in. In the normal, non 
cross
+  # compiling case, jmod execution has to wait until the exploded-image
+  # is completely done. Otherwise the optimization target may be changing
+  # module-info.class files while a jmod instance is trying to read them.
    ifneq ($(CREATING_BUILDJDK), true)
-    $(JMOD_TARGETS): java
+    $(JMOD_TARGETS): exploded-image
    endif

    ifeq ($(CREATE_BUILDJDK), true)


/Erik