public XStream(ReflectionProvider reflectionProvider, HierarchicalStreamDriver driver, ClassLoader classLoader, Mapper mapper) {
this(reflectionProvider, driver, new ClassLoaderReference(classLoader), mapper, new DefaultConverterLookup());
}
测试代码如下：
12345678
public static void main(String[] args) throws Exception {
int i=0;
while (true) {
XStream xs = new XStream(null,null, new ClassLoaderReference(XStreamTest.class.getClassLoader()),null, new DefaultConverterLookup());
xs.toString();
xs=null;
}
}
main@1, prio=5, in group 'main', status: 'RUNNING'
at com.thoughtworks.xstream.core.util.CompositeClassLoader.loadClass(CompositeClassLoader.java:53)
at java.lang.Class.forName0(Class.java:-1)
at java.lang.Class.forName(Class.java:249)
at com.thoughtworks.xstream.XStream.buildMapperDynamically(XStream.java:191)
at com.thoughtworks.xstream.XStream.buildMapper(XStream.java:170)
at com.thoughtworks.xstream.XStream.<init>(XStream.java:142)
at com.thoughtworks.xstream.XStream.<init>(XStream.java:116)
at com.BBBB.main(BBBB.java:15)
void SharedHeap::process_strong_roots(bool activate_scope,
bool collecting_perm_gen,
ScanningOption so,
OopClosure* roots,
CodeBlobClosure* code_roots,
OopsInGenClosure* perm_blk) {
StrongRootsScope srs(this, activate_scope);
// General strong roots.
assert(_strong_roots_parity != 0, "must have called prologue code");
// _n_termination for _process_strong_tasks should be set up stream
// in a method not running in a GC worker. Otherwise the GC worker
// could be trying to change the termination condition while the task
// is executing in another GC worker.
if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
Universe::oops_do(roots);
// Consider perm-gen discovered lists to be strong.
//将perm gen的非强引用标记为root的一部分
perm_gen()->ref_processor()->weak_oops_do(roots);
}
// Global (strong) JNI handles
if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
JNIHandles::oops_do(roots);
// All threads execute this; the individual threads are task groups.
if (ParallelGCThreads > 0) {
Threads::possibly_parallel_oops_do(roots, code_roots);
} else {
Threads::oops_do(roots, code_roots);
}
if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
ObjectSynchronizer::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
FlatProfiler::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
Management::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
JvmtiExport::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
if (so & SO_AllClasses) {
SystemDictionary::oops_do(roots);
} else if (so & SO_SystemClasses) {
SystemDictionary::always_strong_oops_do(roots);
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
//JavaObjectsInPerm为false，那么String intern的对象已经class对象都是存在heap里的，否则都存在perm里
if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
//虽然不回收perm，但是interned的String对象不在perm里，那么还是需要遍历下StringTable里的String对象，因为这些对象在heap里
StringTable::oops_do(roots);
}
if (JavaObjectsInPerm) {
// Verify the string table contents are in the perm gen
NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
if (so & SO_CodeCache) {
// (Currently, CMSCollector uses this to do intermediate-strength collections.)
assert(collecting_perm_gen, "scanning all of code cache");
assert(code_roots != NULL, "must supply closure for code cache");
if (code_roots != NULL) {
CodeCache::blobs_do(code_roots);
}
} else if (so & (SO_SystemClasses|SO_AllClasses)) {
if (!collecting_perm_gen) {
// If we are collecting from class statics, but we are not going to
// visit all of the CodeCache, collect from the non-perm roots if any.
// This makes the code cache function temporarily as a source of strong
// roots for oops, until the next major collection.
//
// If collecting_perm_gen is true, we require that this phase will call
// CodeCache::do_unloading. This will kill off nmethods with expired
// weak references, such as stale invokedynamic targets.
CodeCache::scavenge_root_nmethods_do(code_roots);
}
}
// Verify that the code cache contents are not subject to
// movement by a scavenging collection.
DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
}
if (!collecting_perm_gen) {
//如果是不回收perm，那找出所有perm指向new的对象
// All threads perform this; coordination is handled internally.
rem_set()->younger_refs_iterate(perm_gen(), perm_blk);//perm的level是-1
}
_process_strong_tasks->all_tasks_completed();
}
