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8184765: Dynamically resize SystemDictionary

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Implemented dynamic resizing, which triggers when load factor is too high

Reviewed-by: coleenp, rehn
This commit is contained in:
Gerard Ziemski 2017-11-02 11:00:34 -05:00
parent e878b3272b
commit a043febf6f
14 changed files with 415 additions and 85 deletions
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44
src/hotspot/share/classfile/classLoaderData.cpp
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@ -604,40 +604,27 @@ ModuleEntryTable* ClassLoaderData::modules() {
const int _boot_loader_dictionary_size = 1009;
const int _default_loader_dictionary_size = 107;
const int _prime_array_size = 8; // array of primes for system dictionary size
const int _average_depth_goal = 3; // goal for lookup length
const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
// Calculate a "good" dictionary size based
// on predicted or current loaded classes count.
static int calculate_dictionary_size(int classcount) {
int newsize = _primelist[0];
if (classcount > 0 && !DumpSharedSpaces) {
int index = 0;
int desiredsize = classcount/_average_depth_goal;
for (newsize = _primelist[index]; index < _prime_array_size -1;
newsize = _primelist[++index]) {
if (desiredsize <= newsize) {
break;
}
}
}
return newsize;
}
Dictionary* ClassLoaderData::create_dictionary() {
assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
int size;
bool resizable = false;
if (_the_null_class_loader_data == NULL) {
size = _boot_loader_dictionary_size;
resizable = true;
} else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
size = 1; // there's only one class in relection class loader and no initiated classes
} else if (is_system_class_loader_data()) {
size = calculate_dictionary_size(PredictedLoadedClassCount);
size = _boot_loader_dictionary_size;
resizable = true;
} else {
size = _default_loader_dictionary_size;
resizable = true;
}
return new Dictionary(this, size);
if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
resizable = false;
}
return new Dictionary(this, size, resizable);
}
// Unloading support
@ -1325,6 +1312,19 @@ void ClassLoaderDataGraph::purge() {
}
}
int ClassLoaderDataGraph::resize_if_needed() {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
int resized = 0;
if (Dictionary::does_any_dictionary_needs_resizing()) {
FOR_ALL_DICTIONARY(cld) {
if (cld->dictionary()->resize_if_needed()) {
resized++;
}
}
}
return resized;
}
void ClassLoaderDataGraph::post_class_unload_events() {
#if INCLUDE_TRACE
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");