diff --git a/src/hotspot/share/classfile/classLoader.cpp b/src/hotspot/share/classfile/classLoader.cpp
index 8dcd7985a40f2..835b6685c7b49 100644
--- a/src/hotspot/share/classfile/classLoader.cpp
+++ b/src/hotspot/share/classfile/classLoader.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -141,8 +141,9 @@ PerfCounter* ClassLoader::_unsafe_defineClassCallCounter = NULL;
GrowableArray<ModuleClassPathList*>* ClassLoader::_patch_mod_entries = NULL;
GrowableArray<ModuleClassPathList*>* ClassLoader::_exploded_entries = NULL;
ClassPathEntry* ClassLoader::_jrt_entry = NULL;
-ClassPathEntry* ClassLoader::_first_append_entry = NULL;
-ClassPathEntry* ClassLoader::_last_append_entry = NULL;
+
+ClassPathEntry* volatile ClassLoader::_first_append_entry_list = NULL;
+ClassPathEntry* volatile ClassLoader::_last_append_entry = NULL;
#if INCLUDE_CDS
ClassPathEntry* ClassLoader::_app_classpath_entries = NULL;
ClassPathEntry* ClassLoader::_last_app_classpath_entry = NULL;
@@ -815,7 +816,7 @@ ClassPathZipEntry* ClassLoader::create_class_path_zip_entry(const char *path, bo
// returns true if entry already on class path
bool ClassLoader::contains_append_entry(const char* name) {
- ClassPathEntry* e = _first_append_entry;
+ ClassPathEntry* e = first_append_entry();
while (e != NULL) {
// assume zip entries have been canonicalized
if (strcmp(name, e->name()) == 0) {
@@ -826,11 +827,14 @@ bool ClassLoader::contains_append_entry(const char* name) {
return false;
}
+// The boot append entries are added with a lock, and read lock free.
void ClassLoader::add_to_boot_append_entries(ClassPathEntry *new_entry) {
if (new_entry != NULL) {
+ MutexLocker ml(Bootclasspath_lock, Mutex::_no_safepoint_check_flag);
if (_last_append_entry == NULL) {
- assert(_first_append_entry == NULL, "boot loader's append class path entry list not empty");
- _first_append_entry = _last_append_entry = new_entry;
+ _last_append_entry = new_entry;
+ assert(first_append_entry() == NULL, "boot loader's append class path entry list not empty");
+ Atomic::release_store(&_first_append_entry_list, new_entry);
} else {
_last_append_entry->set_next(new_entry);
_last_append_entry = new_entry;
@@ -944,7 +948,7 @@ void ClassLoader::print_bootclasspath() {
}
// appended entries
- e = _first_append_entry;
+ e = first_append_entry();
while (e != NULL) {
tty->print("%s ;", e->name());
e = e->next();
@@ -1252,7 +1256,7 @@ InstanceKlass* ClassLoader::load_class(Symbol* name, bool search_append_only, TR
assert(classpath_index == 0, "The classpath_index has been incremented incorrectly");
classpath_index = 1;
- e = _first_append_entry;
+ e = first_append_entry();
while (e != NULL) {
stream = e->open_stream(file_name, CHECK_NULL);
if (NULL != stream) {
@@ -1427,7 +1431,7 @@ void ClassLoader::record_result(InstanceKlass* ik, const ClassFileStream* stream
// Initialize the class loader's access to methods in libzip. Parse and
// process the boot classpath into a list ClassPathEntry objects. Once
// this list has been created, it must not change order (see class PackageInfo)
-// it can be appended to and is by jvmti and the kernel vm.
+// it can be appended to and is by jvmti.
void ClassLoader::initialize() {
EXCEPTION_MARK;
diff --git a/src/hotspot/share/classfile/classLoader.hpp b/src/hotspot/share/classfile/classLoader.hpp
index 9e0dde6464ee7..e00892c423d9e 100644
--- a/src/hotspot/share/classfile/classLoader.hpp
+++ b/src/hotspot/share/classfile/classLoader.hpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -53,6 +53,7 @@ class ClassPathEntry : public CHeapObj<mtClass> {
ClassPathEntry* next() const;
virtual ~ClassPathEntry() {}
void set_next(ClassPathEntry* next);
+
virtual bool is_modules_image() const { return false; }
virtual bool is_jar_file() const { return false; }
// Is this entry created from the "Class-path" attribute from a JAR Manifest?
@@ -214,9 +215,13 @@ class ClassLoader: AllStatic {
// 3. the boot loader's append path
// [-Xbootclasspath/a]; [jvmti appended entries]
// Note: boot loader append path does not support named modules.
- static ClassPathEntry* _first_append_entry;
+ static ClassPathEntry* volatile _first_append_entry_list;
+ static ClassPathEntry* first_append_entry() {
+ return Atomic::load_acquire(&_first_append_entry_list);
+ }
+
// Last entry in linked list of appended ClassPathEntry instances
- static ClassPathEntry* _last_append_entry;
+ static ClassPathEntry* volatile _last_append_entry;
// Info used by CDS
CDS_ONLY(static ClassPathEntry* _app_classpath_entries;)
@@ -234,7 +239,7 @@ class ClassLoader: AllStatic {
CDS_ONLY(static ClassPathEntry* app_classpath_entries() {return _app_classpath_entries;})
CDS_ONLY(static ClassPathEntry* module_path_entries() {return _module_path_entries;})
- static bool has_bootclasspath_append() { return _first_append_entry != NULL; }
+ static bool has_bootclasspath_append() { return first_append_entry() != NULL; }
protected:
// Initialization:
diff --git a/src/hotspot/share/classfile/classLoader.inline.hpp b/src/hotspot/share/classfile/classLoader.inline.hpp
index 5d10272e522eb..aa362f3112c06 100644
--- a/src/hotspot/share/classfile/classLoader.inline.hpp
+++ b/src/hotspot/share/classfile/classLoader.inline.hpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -48,7 +48,7 @@ inline ClassPathEntry* ClassLoader::classpath_entry(int n) {
// the _jrt_entry is not included in the _first_append_entry
// linked list, it must be accounted for when comparing the
// class path vs. the shared archive class path.
- ClassPathEntry* e = ClassLoader::_first_append_entry;
+ ClassPathEntry* e = first_append_entry();
while (--n >= 1) {
assert(e != NULL, "Not that many classpath entries.");
e = e->next();
@@ -72,7 +72,7 @@ inline int ClassLoader::num_boot_classpath_entries() {
Arguments::assert_is_dumping_archive();
assert(has_jrt_entry(), "must have a java runtime image");
int num_entries = 1; // count the runtime image
- ClassPathEntry* e = ClassLoader::_first_append_entry;
+ ClassPathEntry* e = first_append_entry();
while (e != NULL) {
num_entries ++;
e = e->next();
@@ -82,7 +82,7 @@ inline int ClassLoader::num_boot_classpath_entries() {
inline ClassPathEntry* ClassLoader::get_next_boot_classpath_entry(ClassPathEntry* e) {
if (e == ClassLoader::_jrt_entry) {
- return ClassLoader::_first_append_entry;
+ return first_append_entry();
} else {
return e->next();
}
diff --git a/src/hotspot/share/prims/jvmtiEnv.cpp b/src/hotspot/share/prims/jvmtiEnv.cpp
index 4559f9d279d1f..d3694e342bb8f 100644
--- a/src/hotspot/share/prims/jvmtiEnv.cpp
+++ b/src/hotspot/share/prims/jvmtiEnv.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -659,13 +659,6 @@ JvmtiEnv::AddToBootstrapClassLoaderSearch(const char* segment) {
return JVMTI_ERROR_ILLEGAL_ARGUMENT;
}
- // lock the loader
- Thread* thread = Thread::current();
- HandleMark hm(thread);
- Handle loader_lock = Handle(thread, SystemDictionary::system_loader_lock());
-
- ObjectLocker ol(loader_lock, thread);
-
// add the jar file to the bootclasspath
log_info(class, load)("opened: %s", zip_entry->name());
#if INCLUDE_CDS
diff --git a/src/hotspot/share/runtime/mutexLocker.cpp b/src/hotspot/share/runtime/mutexLocker.cpp
index fea5e23cf43cd..4d74d70ba509f 100644
--- a/src/hotspot/share/runtime/mutexLocker.cpp
+++ b/src/hotspot/share/runtime/mutexLocker.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -156,6 +156,7 @@ Mutex* CDSLambda_lock = NULL;
Mutex* DumpRegion_lock = NULL;
Mutex* ClassListFile_lock = NULL;
#endif // INCLUDE_CDS
+Mutex* Bootclasspath_lock = NULL;
#if INCLUDE_JVMCI
Monitor* JVMCI_lock = NULL;
@@ -352,6 +353,7 @@ void mutex_init() {
def(DumpRegion_lock , PaddedMutex , leaf, true, _safepoint_check_never);
def(ClassListFile_lock , PaddedMutex , leaf, true, _safepoint_check_never);
#endif // INCLUDE_CDS
+ def(Bootclasspath_lock , PaddedMutex , leaf, false, _safepoint_check_never);
#if INCLUDE_JVMCI
def(JVMCI_lock , PaddedMonitor, nonleaf+2, true, _safepoint_check_always);
diff --git a/src/hotspot/share/runtime/mutexLocker.hpp b/src/hotspot/share/runtime/mutexLocker.hpp
index a4a5865cf3c62..de9fe972c1a6e 100644
--- a/src/hotspot/share/runtime/mutexLocker.hpp
+++ b/src/hotspot/share/runtime/mutexLocker.hpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -158,6 +158,8 @@ extern Mutex* CodeHeapStateAnalytics_lock; // lock print functions against
extern Monitor* JVMCI_lock; // Monitor to control initialization of JVMCI
#endif
+extern Mutex* Bootclasspath_lock;
+
extern Mutex* tty_lock; // lock to synchronize output.
// A MutexLocker provides mutual exclusion with respect to a given mutex