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src/jdk.jdwp.agent/share/native/libjdwp/classTrack.c
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rev 57484 : 8227269: Slow class loading when running with JDWP
*** 43,294 ****
#include "util.h"
#include "bag.h"
#include "classTrack.h"
! /* ClassTrack hash table slot count */
! #define CT_HASH_SLOT_COUNT 263 /* Prime which eauals 4k+3 for some k */
typedef struct KlassNode {
! jclass klass; /* weak global reference */
char *signature; /* class signature */
struct KlassNode *next; /* next node in this slot */
} KlassNode;
/*
! * Hash table of prepared classes. Each entry is a pointer
! * to a linked list of KlassNode.
*/
! static KlassNode **table;
/*
! * Return slot in hash table to use for this class.
*/
! static jint
! hashKlass(jclass klass)
! {
! jint hashCode = objectHashCode(klass);
! return abs(hashCode) % CT_HASH_SLOT_COUNT;
! }
/*
! * Transfer a node (which represents klass) from the current
! * table to the new table.
*/
! static void
! transferClass(JNIEnv *env, jclass klass, KlassNode **newTable) {
! jint slot = hashKlass(klass);
! KlassNode **head = &table[slot];
! KlassNode **newHead = &newTable[slot];
! KlassNode **nodePtr;
! KlassNode *node;
!
! /* Search the node list of the current table for klass */
! for (nodePtr = head; node = *nodePtr, node != NULL; nodePtr = &(node->next)) {
! if (isSameObject(env, klass, node->klass)) {
! /* Match found transfer node */
! /* unlink from old list */
! *nodePtr = node->next;
!
! /* insert in new list */
! node->next = *newHead;
! *newHead = node;
!
! return;
! }
! }
! /* we haven't found the class, only unloads should have happenned,
! * so the only reason a class should not have been found is
! * that it is not prepared yet, in which case we don't want it.
! * Asset that the above is true.
*/
! /**** the HotSpot VM doesn't create prepare events for some internal classes ***
! JDI_ASSERT_MSG((classStatus(klass) &
! (JVMTI_CLASS_STATUS_PREPARED|JVMTI_CLASS_STATUS_ARRAY))==0,
! classSignature(klass));
! ***/
! }
/*
! * Delete a hash table of classes.
! * The signatures of classes in the table are returned.
*/
! static struct bag *
! deleteTable(JNIEnv *env, KlassNode *oldTable[])
{
! struct bag *signatures = bagCreateBag(sizeof(char*), 10);
! jint slot;
!
! if (signatures == NULL) {
! EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY,"signatures");
}
! for (slot = 0; slot < CT_HASH_SLOT_COUNT; slot++) {
! KlassNode *node = oldTable[slot];
!
! while (node != NULL) {
! KlassNode *next;
! char **sigSpot;
!
! /* Add signature to the signature bag */
! sigSpot = bagAdd(signatures);
! if (sigSpot == NULL) {
! EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY,"signature bag");
! }
! *sigSpot = node->signature;
!
! /* Free weak ref and the node itself */
! JNI_FUNC_PTR(env,DeleteWeakGlobalRef)(env, node->klass);
! next = node->next;
! jvmtiDeallocate(node);
! node = next;
}
}
- jvmtiDeallocate(oldTable);
! return signatures;
}
/*
! * Called after class unloads have occurred. Creates a new hash table
! * of currently loaded prepared classes.
! * The signatures of classes which were unloaded (not present in the
! * new table) are returned.
*/
struct bag *
classTrack_processUnloads(JNIEnv *env)
{
! KlassNode **newTable;
! struct bag *unloadedSignatures;
!
! unloadedSignatures = NULL;
! newTable = jvmtiAllocate(CT_HASH_SLOT_COUNT * sizeof(KlassNode *));
! if (newTable == NULL) {
! EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY, "classTrack table");
! } else {
!
! (void)memset(newTable, 0, CT_HASH_SLOT_COUNT * sizeof(KlassNode *));
!
! WITH_LOCAL_REFS(env, 1) {
!
! jint classCount;
! jclass *classes;
! jvmtiError error;
! int i;
!
! error = allLoadedClasses(&classes, &classCount);
! if ( error != JVMTI_ERROR_NONE ) {
! jvmtiDeallocate(newTable);
! EXIT_ERROR(error,"loaded classes");
! } else {
!
! /* Transfer each current class into the new table */
! for (i=0; i<classCount; i++) {
! jclass klass = classes[i];
! transferClass(env, klass, newTable);
! }
! jvmtiDeallocate(classes);
!
! /* Delete old table, install new one */
! unloadedSignatures = deleteTable(env, table);
! table = newTable;
! }
!
! } END_WITH_LOCAL_REFS(env)
!
! }
!
! return unloadedSignatures;
}
/*
! * Add a class to the prepared class hash table.
! * Assumes no duplicates.
*/
void
classTrack_addPreparedClass(JNIEnv *env, jclass klass)
{
- jint slot = hashKlass(klass);
- KlassNode **head = &table[slot];
- KlassNode *node;
jvmtiError error;
! if (gdata->assertOn) {
! /* Check this is not a duplicate */
! for (node = *head; node != NULL; node = node->next) {
! if (isSameObject(env, klass, node->klass)) {
! JDI_ASSERT_FAILED("Attempting to insert duplicate class");
! break;
}
}
}
! node = jvmtiAllocate(sizeof(KlassNode));
if (node == NULL) {
EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY,"KlassNode");
}
error = classSignature(klass, &(node->signature), NULL);
if (error != JVMTI_ERROR_NONE) {
jvmtiDeallocate(node);
EXIT_ERROR(error,"signature");
}
! if ((node->klass = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, klass)) == NULL) {
jvmtiDeallocate(node->signature);
jvmtiDeallocate(node);
! EXIT_ERROR(AGENT_ERROR_NULL_POINTER,"NewWeakGlobalRef");
}
/* Insert the new node */
! node->next = *head;
! *head = node;
}
/*
! * Called once to build the initial prepared class hash table.
*/
void
classTrack_initialize(JNIEnv *env)
{
WITH_LOCAL_REFS(env, 1) {
jint classCount;
jclass *classes;
jvmtiError error;
jint i;
error = allLoadedClasses(&classes, &classCount);
if ( error == JVMTI_ERROR_NONE ) {
! table = jvmtiAllocate(CT_HASH_SLOT_COUNT * sizeof(KlassNode *));
! if (table != NULL) {
! (void)memset(table, 0, CT_HASH_SLOT_COUNT * sizeof(KlassNode *));
! for (i=0; i<classCount; i++) {
jclass klass = classes[i];
jint status;
! jint wanted =
! (JVMTI_CLASS_STATUS_PREPARED|JVMTI_CLASS_STATUS_ARRAY);
!
! /* We only want prepared classes and arrays */
status = classStatus(klass);
! if ( (status & wanted) != 0 ) {
classTrack_addPreparedClass(env, klass);
}
}
- } else {
- jvmtiDeallocate(classes);
- EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY,"KlassNode");
- }
jvmtiDeallocate(classes);
} else {
EXIT_ERROR(error,"loaded classes array");
}
} END_WITH_LOCAL_REFS(env)
}
void
classTrack_reset(void)
{
}
--- 43,323 ----
#include "util.h"
#include "bag.h"
#include "classTrack.h"
! /* ClassTrack table slot count */
! #define CT_SLOT_COUNT 263 /* Prime which eauals 4k+3 for some k */
typedef struct KlassNode {
! jlong klass_tag; /* Klass's tag in tracking env */
char *signature; /* class signature */
struct KlassNode *next; /* next node in this slot */
} KlassNode;
/*
! * Table mapping tag % CT_SLOT_COUNT to linked-list of KlassNode*.
*/
! static KlassNode** table;
/*
! * The JVMTI tracking env to keep track of klass tags, for class-unloads
*/
! static jvmtiEnv* trackingEnv;
/*
! * The current highest tag number
*/
! static jlong currentClassTag;
! /*
! * Lock to protect deletedSignatureBag
! */
! static jrawMonitorID deletedSignatureLock;
! /*
! * A bag containing all the deleted classes' signatures. Must be accessed under
! * deletedTagLock,
*/
! struct bag* deletedSignatureBag;
/*
! * Callback when classes are freed, Finds the signature and remembers it in deletedSignatureBag.
*/
! static void JNICALL
! cbTrackingObjectFree(jvmtiEnv* jvmti_env, jlong tag)
{
! debugMonitorEnter(deletedSignatureLock);
! if (currentClassTag == -1) {
! // Class tracking not initialized, nobody's interested
! debugMonitorExit(deletedSignatureLock);
! return;
}
! // Find deleted KlassNode
! size_t idx = tag % CT_SLOT_COUNT;
! KlassNode** klass_ptr = &table[idx];
! KlassNode* klass = *klass_ptr;
!
! // Tag not found? Ignore.
! if (klass == NULL) {
! debugMonitorExit(deletedSignatureLock);
! return;
! }
! // Scan linked-list.
! jlong found_tag = klass->klass_tag;
! while (klass != NULL && found_tag != tag) {
! klass_ptr = &klass->next;
! klass = *klass_ptr;
! found_tag = klass->klass_tag;
}
+
+ // Tag not found? Ignore.
+ if (found_tag != tag) {
+ debugMonitorExit(deletedSignatureLock);
+ return;
}
! // At this point we have the KlassNode corresponding to the tag
! // in klass, and the pointer to it in klass_node.
! // Remember the unloaded signature.
! *(char**)bagAdd(deletedSignatureBag) = klass->signature;
!
! // Unlink the KlassNode.
! *klass_ptr = klass->next;
! jvmtiDeallocate(klass);
!
! // Done.
! debugMonitorExit(deletedSignatureLock);
}
/*
! * Called after class unloads have occurred.
! * The signatures of classes which were unloaded are returned.
*/
struct bag *
classTrack_processUnloads(JNIEnv *env)
{
! debugMonitorEnter(deletedSignatureLock);
! if (currentClassTag == -1) {
! // Class tracking not initialized, nobody's interested
! debugMonitorExit(deletedSignatureLock);
! return bagCreateBag(sizeof(char*), 0);
! }
! struct bag* deleted = deletedSignatureBag;
! deletedSignatureBag = bagCreateBag(sizeof(char*), 10);
! debugMonitorExit(deletedSignatureLock);
! return deleted;
}
/*
! * Add a class to the prepared class table.
*/
void
classTrack_addPreparedClass(JNIEnv *env, jclass klass)
{
jvmtiError error;
! debugMonitorEnter(deletedSignatureLock);
! if (currentClassTag == -1) {
! // Class tracking not initialized yet, nobody's interested
! debugMonitorExit(deletedSignatureLock);
! return;
}
+
+ /* Check this is not a duplicate */
+ jlong tag;
+ error = JVMTI_FUNC_PTR(trackingEnv, GetTag)(trackingEnv, klass, &tag);
+ if (error != JVMTI_ERROR_NONE) {
+ EXIT_ERROR(error, "Unable to GetTag with class trackingEnv");
}
+ if (tag != 0l) {
+ debugMonitorExit(deletedSignatureLock);
+ return; // Already added
}
! KlassNode* node = jvmtiAllocate(sizeof(KlassNode));
if (node == NULL) {
EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY,"KlassNode");
}
error = classSignature(klass, &(node->signature), NULL);
if (error != JVMTI_ERROR_NONE) {
jvmtiDeallocate(node);
EXIT_ERROR(error,"signature");
}
! node->klass_tag = ++currentClassTag;
! error = JVMTI_FUNC_PTR(trackingEnv, SetTag)(trackingEnv, klass, node->klass_tag);
! if (error != JVMTI_ERROR_NONE) {
jvmtiDeallocate(node->signature);
jvmtiDeallocate(node);
! EXIT_ERROR(error,"SetTag");
}
/* Insert the new node */
! size_t idx = node->klass_tag % CT_SLOT_COUNT;
! node->next = table[idx];
! table[idx] = node;
! debugMonitorExit(deletedSignatureLock);
! }
!
! static jboolean
! setupEvents()
! {
! jvmtiCapabilities caps;
! memset(&caps, 0, sizeof(caps));
! caps.can_generate_object_free_events = 1;
! jvmtiError error = JVMTI_FUNC_PTR(trackingEnv, AddCapabilities)(trackingEnv, &caps);
! if (error != JVMTI_ERROR_NONE) {
! return JNI_FALSE;
! }
! jvmtiEventCallbacks cb;
! memset(&cb, 0, sizeof(cb));
! cb.ObjectFree = cbTrackingObjectFree;
! error = JVMTI_FUNC_PTR(trackingEnv, SetEventCallbacks)(trackingEnv, &cb, sizeof(cb));
! if (error != JVMTI_ERROR_NONE) {
! return JNI_FALSE;
! }
! error = JVMTI_FUNC_PTR(trackingEnv, SetEventNotificationMode)(trackingEnv, JVMTI_ENABLE, JVMTI_EVENT_OBJECT_FREE, NULL);
! if (error != JVMTI_ERROR_NONE) {
! return JNI_FALSE;
! }
! return JNI_TRUE;
}
/*
! * Called once to initialize class-tracking.
*/
void
classTrack_initialize(JNIEnv *env)
{
+ trackingEnv = getSpecialJvmti();
+ if (trackingEnv == NULL) {
+ EXIT_ERROR(AGENT_ERROR_INTERNAL, "Failed to allocate tag-tracking jvmtiEnv");
+ }
+ deletedSignatureLock = debugMonitorCreate("Deleted class tag lock");
+ deletedSignatureBag = bagCreateBag(sizeof(char*), 10);
+ currentClassTag = -1l;
+ table = NULL;
+ }
+
+ /*
+ * Called to activate class-tracking when a listener registers for EI_GC_FINISH.
+ */
+ void
+ classTrack_activate(JNIEnv *env)
+ {
+ if (!setupEvents()) {
+ EXIT_ERROR(AGENT_ERROR_INTERNAL, "Unable to setup ObjectFree tracking");
+ }
+ currentClassTag = 0l;
+ table = jvmtiAllocate(CT_SLOT_COUNT * sizeof(KlassNode*));
+ if (table != NULL) {
+ (void)memset(table, 0, CT_SLOT_COUNT * sizeof(KlassNode*));
+ } else {
+ EXIT_ERROR(AGENT_ERROR_OUT_OF_MEMORY, "failed allocating class-track table");
+ }
+
WITH_LOCAL_REFS(env, 1) {
jint classCount;
jclass *classes;
jvmtiError error;
jint i;
error = allLoadedClasses(&classes, &classCount);
if ( error == JVMTI_ERROR_NONE ) {
! for (i = 0; i < classCount; i++) {
jclass klass = classes[i];
jint status;
! jint wanted = JVMTI_CLASS_STATUS_PREPARED | JVMTI_CLASS_STATUS_ARRAY;
status = classStatus(klass);
! if ((status & wanted) != 0) {
classTrack_addPreparedClass(env, klass);
}
}
jvmtiDeallocate(classes);
} else {
EXIT_ERROR(error,"loaded classes array");
}
} END_WITH_LOCAL_REFS(env)
+ }
+ static jboolean
+ cleanDeleted(void *signatureVoid, void *arg)
+ {
+ char* sig = (char*)signatureVoid;
+ jvmtiDeallocate(sig);
+ return JNI_TRUE;
}
+ /*
+ * Called when agent detaches.
+ */
void
classTrack_reset(void)
{
+ int idx;
+ debugMonitorEnter(deletedSignatureLock);
+
+ for (idx = 0; idx < CT_SLOT_COUNT; ++idx) {
+ KlassNode* node = table[idx];
+ while (node != NULL) {
+ KlassNode* next = node->next;
+ jvmtiDeallocate(node->signature);
+ jvmtiDeallocate(node);
+ node = next;
+ }
+ }
+ jvmtiDeallocate(table);
+
+ bagEnumerateOver(deletedSignatureBag, cleanDeleted, NULL);
+ bagDestroyBag(deletedSignatureBag);
+
+ currentClassTag = -1;
+
+ (void)JVMTI_FUNC_PTR(trackingEnv,DisposeEnvironment)(trackingEnv);
+ trackingEnv = NULL;
+
+ debugMonitorExit(deletedSignatureLock);
}
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