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8207778: Add locking to ModuleEntry and PackageEntry tables

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Restructure ClassLoaderDataGraph code to simplify using locks in SystemDictionary::do_unloading()

Reviewed-by: lfoltan, coleenp
This commit is contained in:
Harold Seigel 2018-08-10 09:30:26 -04:00
parent 092e9e4f81
commit 83b2fb5b0d
7 changed files with 37 additions and 28 deletions
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47
src/hotspot/share/classfile/classLoaderData.cpp
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@ -1418,27 +1418,6 @@ bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) {
}
if (seen_dead_loader) {
data = _head;
while (data != NULL) {
// Remove entries in the dictionary of live class loader that have
// initiated loading classes in a dead class loader.
if (data->dictionary() != NULL) {
data->dictionary()->do_unloading();
}
// Walk a ModuleEntry's reads, and a PackageEntry's exports
// lists to determine if there are modules on those lists that are now
// dead and should be removed. A module's life cycle is equivalent
// to its defining class loader's life cycle. Since a module is
// considered dead if its class loader is dead, these walks must
// occur after each class loader's aliveness is determined.
if (data->packages() != NULL) {
data->packages()->purge_all_package_exports();
}
if (data->modules_defined()) {
data->modules()->purge_all_module_reads();
}
data = data->next();
}
JFR_ONLY(post_class_unload_events();)
}
@ -1447,6 +1426,32 @@ bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) {
return seen_dead_loader;
}
// There's at least one dead class loader. Purge refererences of healthy module
// reads lists and package export lists to modules belonging to dead loaders.
void ClassLoaderDataGraph::clean_module_and_package_info() {
ClassLoaderData* data = _head;
while (data != NULL) {
// Remove entries in the dictionary of live class loader that have
// initiated loading classes in a dead class loader.
if (data->dictionary() != NULL) {
data->dictionary()->do_unloading();
}
// Walk a ModuleEntry's reads, and a PackageEntry's exports
// lists to determine if there are modules on those lists that are now
// dead and should be removed. A module's life cycle is equivalent
// to its defining class loader's life cycle. Since a module is
// considered dead if its class loader is dead, these walks must
// occur after each class loader's aliveness is determined.
if (data->packages() != NULL) {
data->packages()->purge_all_package_exports();
}
if (data->modules_defined()) {
data->modules()->purge_all_module_reads();
}
data = data->next();
}
}
void ClassLoaderDataGraph::purge() {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
ClassLoaderData* list = _unloading;