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8232788: Move biased locking initalization

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Reviewed-by: pchilanomate, dholmes
This commit is contained in:
Coleen Phillimore 2019-10-24 08:52:33 -04:00
parent 31ab60e211
commit 9308d18580
3 changed files with 18 additions and 21 deletions
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20
src/hotspot/share/classfile/systemDictionary.cpp
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@ -2132,26 +2132,6 @@ void SystemDictionary::update_dictionary(unsigned int d_hash,
{
MutexLocker mu1(SystemDictionary_lock, THREAD);
// See whether biased locking is enabled and if so set it for this
// klass.
// Note that this must be done past the last potential blocking
// point / safepoint. We might enable biased locking lazily using a
// VM_Operation to iterate the SystemDictionary and installing the
// biasable mark word into each InstanceKlass's prototype header.
// To avoid race conditions where we accidentally miss enabling the
// optimization for one class in the process of being added to the
// dictionary, we must not safepoint after the test of
// BiasedLocking::enabled().
if (UseBiasedLocking && BiasedLocking::enabled()) {
// Set biased locking bit for all loaded classes; it will be
// cleared if revocation occurs too often for this type
// NOTE that we must only do this when the class is initally
// defined, not each time it is referenced from a new class loader
if (k->class_loader() == class_loader()) {
k->set_prototype_header(markWord::biased_locking_prototype());
}
}
// Make a new dictionary entry.
Dictionary* dictionary = loader_data->dictionary();
InstanceKlass* sd_check = find_class(d_hash, name, dictionary);