archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-26 22:34:27 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8159262: Walking PackageEntry Export and ModuleEntry Reads Must Occur Only When Neccessary And Wait Until ClassLoader's Aliveness Determined

Browse source 
Fixed an issue in class unloading to delay walk until class loader's aliveness is determined of modularity lists to remove dead modules

Reviewed-by: coleenp, dholmes, sspitsyn, zgu
This commit is contained in:
Lois Foltan 2016-06-28 10:11:01 -04:00
parent 651e15fda6
commit 92eb334c91
16 changed files with 807 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

52
hotspot/src/share/vm/classfile/moduleEntry.cpp
View file

@ -40,7 +40,6 @@
ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
void ModuleEntry::set_location(Symbol* location) {
if (_location != NULL) {
// _location symbol's refcounts are managed by ModuleEntry,
@ -115,10 +114,35 @@ void ModuleEntry::add_read(ModuleEntry* m) {
// Lazily create a module's reads list
_reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
}
// Determine, based on this newly established read edge to module m,
// if this module's read list should be walked at a GC safepoint.
set_read_walk_required(m->loader_data());
// Establish readability to module m
_reads->append_if_missing(m);
}
}
// If the module's loader, that a read edge is being established to, is
// not the same loader as this module's and is not one of the 3 builtin
// class loaders, then this module's reads list must be walked at GC
// safepoint. Modules have the same life cycle as their defining class
// loaders and should be removed if dead.
void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
assert_locked_or_safepoint(Module_lock);
if (!_must_walk_reads &&
loader_data() != m_loader_data &&
!m_loader_data->is_builtin_class_loader_data()) {
_must_walk_reads = true;
if (log_is_enabled(Trace, modules)) {
ResourceMark rm;
log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
(name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
}
}
}
bool ModuleEntry::has_reads() const {
assert_locked_or_safepoint(Module_lock);
return ((_reads != NULL) && !_reads->is_empty());
@ -127,14 +151,28 @@ bool ModuleEntry::has_reads() const {
// Purge dead module entries out of reads list.
void ModuleEntry::purge_reads() {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
if (has_reads()) {
if (_must_walk_reads && has_reads()) {
// This module's _must_walk_reads flag will be reset based
// on the remaining live modules on the reads list.
_must_walk_reads = false;
if (log_is_enabled(Trace, modules)) {
ResourceMark rm;
log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
(name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
}
// Go backwards because this removes entries that are dead.
int len = _reads->length();
for (int idx = len - 1; idx >= 0; idx--) {
ModuleEntry* module_idx = _reads->at(idx);
ClassLoaderData* cld = module_idx->loader();
if (cld->is_unloading()) {
ClassLoaderData* cld_idx = module_idx->loader_data();
if (cld_idx->is_unloading()) {
_reads->delete_at(idx);
} else {
// Update the need to walk this module's reads based on live modules
set_read_walk_required(cld_idx);
}
}
}
@ -248,7 +286,7 @@ ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle
entry->set_module(loader_data->add_handle(module_handle));
}
entry->set_loader(loader_data);
entry->set_loader_data(loader_data);
entry->set_version(version);
entry->set_location(location);
@ -379,7 +417,7 @@ void ModuleEntry::print(outputStream* st) {
p2i(this),
name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
p2i(module()),
loader()->loader_name(),
loader_data()->loader_name(),
version() != NULL ? version()->as_C_string() : "NULL",
location() != NULL ? location()->as_C_string() : "NULL",
BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
@ -401,5 +439,5 @@ void ModuleEntryTable::verify() {
}
void ModuleEntry::verify() {
guarantee(loader() != NULL, "A module entry must be associated with a loader.");
guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
}