JDK-8038756 : new WB API :: get/setVMFlag
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2014-03-30
  • Updated: 2016-02-04
  • Resolved: 2014-05-30
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JDK 8 JDK 9
8u40Fixed 9 b20Fixed
Related Reports
Blocks :  
JDK-8044831 - get rid of JMX in compiler/stable/ tests
Blocks :  
JDK-8032449 - Get rid of JMX in test/compiler
Duplicate :  
JDK-8148758 - Compilation fails with "this call site should not be polymorphic"
Relates :  
JDK-8050050 - [TESTBUG] compiler/stable tests fail because WB API is not implemented
Relates :  
JDK-8044575 - [TEST_BUG]testlibrary_tests/whitebox/vm_flags/UintxTest.java failed: assert(!res || TypeEntriesAtCall::arguments_profiling_enabled()) failed: no profiling of arguments
Relates :  
JDK-8061443 - Whitebox get*VMFlag() methods fail with develop flags in product builds
Relates :  
JDK-8050050 - [TESTBUG] compiler/stable tests fail because WB API is not implemented
Description
some bundles doesn't have JMX, at the same time to get more reliable testing we need to get value of vm flags to adjust test's behavior.

the initial idea was to have testSet method, but since some flags can be reread in runtime, it's unsafe to use testSet to get value.
Comments
[~lpriima], backported -- JDK-8054552
08-08-2014
please backport to 8u
07-08-2014
suggested fix for testSet*: template <typename T> bool SetVMFlag(JavaThread* thread, JNIEnv* env, jstring name, T* value, bool (*TAtPut)(const char*, T*, Flag::Flags)) { if (name == NULL) { return false; } ThreadToNativeFromVM ttnfv(thread); // can't be in VM when we call JNI const char* flag_name = env->GetStringUTFChars(name, NULL); bool result = (*TAtPut)(flag_name, value, Flag::INTERNAL); env->ReleaseStringUTFChars(name, flag_name); return result; } WB_ENTRY(jboolean, WB_TestSetBooleanVMFlag(JNIEnv* env, jobject o, jstring name, jboolean value)) bool result = value; SetVMFlag <bool> (thread, env, name, &result, &CommandLineFlags::boolAtPut); return result; WB_END
30-03-2014