jmm: Java Memory Model companion code (volatile, happens-before, DCL)

Runnable jcstress + JUnit companion for the ankurm.com post on the Java Memory Model, double-checked locking, and the volatile fix.
2026-09-30 05:31:29 +00:00
commit f548d9eeb5
22 changed files with 721 additions and 0 deletions
@@ -0,0 +1,21 @@
+$ java -jar target/jcstress.jar -t PlainPublicationTest -jvmArgs "-Xmx256m" -f 2 -iters 15 -time 1000
+
+RUN RESULTS:
+  Interesting tests: No matches.
+
+  Failed tests: No matches.
+
+  Error tests: No matches.
+
+  All remaining tests: 1 matching test results.
+
+.......... [OK] com.ankurm.jmm.PlainPublicationTest
+
+  Results across all configurations:
+
+  RESULT        SAMPLES     FREQ       EXPECT  DESCRIPTION
+    0, 0  3,511,549,619   66.79%   Acceptable  Reader ran before the write was published at all.
+    0, 1              0    0.00%  Interesting  Reordering: the reference was visible before both of its ...
+    1, 0              0    0.00%  Interesting  Reordering: the reference was visible before both of its ...
+    1, 1  1,745,742,499   33.21%   Acceptable  Reader saw the fully-constructed Payload.
+
@@ -0,0 +1,21 @@
+$ java -jar target/jcstress.jar -t VolatilePublicationTest -jvmArgs "-Xmx256m" -f 2 -iters 15 -time 1000
+
+RUN RESULTS:
+  Interesting tests: No matches.
+
+  Failed tests: No matches.
+
+  Error tests: No matches.
+
+  All remaining tests: 1 matching test results.
+
+.......... [OK] com.ankurm.jmm.VolatilePublicationTest
+
+  Results across all configurations:
+
+  RESULT        SAMPLES     FREQ      EXPECT  DESCRIPTION
+    0, 0  4,290,607,784   80.26%  Acceptable  Reader ran before the write was published at all.
+    0, 1              0    0.00%   Forbidden  Would mean the volatile happens-before edge failed to hold.
+    1, 0              0    0.00%   Forbidden  Would mean the volatile happens-before edge failed to hold.
+    1, 1  1,055,076,014   19.74%  Acceptable  Reader saw the fully-constructed Payload.
+
@@ -0,0 +1,21 @@
+$ java -jar target/jcstress.jar -t FinalFieldPublicationTest -jvmArgs "-Xmx256m" -f 2 -iters 15 -time 1000
+
+RUN RESULTS:
+  Interesting tests: No matches.
+
+  Failed tests: No matches.
+
+  Error tests: No matches.
+
+  All remaining tests: 1 matching test results.
+
+.......... [OK] com.ankurm.jmm.FinalFieldPublicationTest
+
+  Results across all configurations:
+
+  RESULT        SAMPLES     FREQ      EXPECT  DESCRIPTION
+    0, 0  3,697,560,129   66.13%  Acceptable  Reader ran before the write was published at all.
+    0, 1              0    0.00%   Forbidden  Would mean the final-field safe-publication guarantee fai...
+    1, 0              0    0.00%   Forbidden  Would mean the final-field safe-publication guarantee fai...
+    1, 1  1,893,699,349   33.87%  Acceptable  Reader saw the fully-constructed FinalPayload.
+
@@ -0,0 +1,19 @@
+$ javac -cp jcstress-core.jar -d out -s gen PlainPublicationTest.java Payload.java   # JDK 21.0.10, no -processorpath
+
+Note: Annotation processing is enabled because one or more processors were found
+  on the class path. A future release of javac may disable annotation processing
+  unless at least one processor is specified by name (-processor), or a search
+  path is specified (--processor-path, --processor-module-path), or annotation
+  processing is enabled explicitly (-proc:only, -proc:full).
+  Use -Xlint:-options to suppress this message.
+  Use -proc:none to disable annotation processing.
+
+$ find gen -type f
+gen/com/ankurm/jmm/PlainPublicationTest_jcstress.java
+
+$ javac -cp jcstress-core.jar -d out -s gen PlainPublicationTest.java Payload.java   # JDK 25.0.4.1+1, no -processorpath
+
+(no output at all - exit code 0)
+
+$ find gen -type f
+(nothing - the processor was never invoked, no error, no warning)
@@ -0,0 +1,6 @@
+$ mvn -q test -pl jmm
+
+-------------------------------------------------------------------------------
+Test set: com.ankurm.jmm.SingletonBehaviorTest
+-------------------------------------------------------------------------------
+Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.067 s -- in com.ankurm.jmm.SingletonBehaviorTest