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8316456: StackWalker may skip Continuation::yield0 frame mistakenly

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Reviewed-by: rpressler, pchilanomate
This commit is contained in:
Mandy Chung 2023-09-21 23:10:49 +00:00
parent 041510dc21
commit c72f00463f
7 changed files with 152 additions and 162 deletions
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151
src/java.base/share/classes/java/lang/StackStreamFactory.java
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@ -192,10 +192,10 @@ final class StackStreamFactory {
*
* Subclass should override this method to change the batch size
*
* @param lastBatchFrameCount number of frames in the last batch; or zero
* @param lastBatchSize last batch size
* @return suggested batch size
*/
protected abstract int batchSize(int lastBatchFrameCount);
protected abstract int batchSize(int lastBatchSize);
/*
* Returns the next batch size, always >= minimum batch size
@ -203,7 +203,7 @@ final class StackStreamFactory {
* Subclass may override this method if the minimum batch size is different.
*/
protected int getNextBatchSize() {
int lastBatchSize = depth == 0 ? 0 : frameBuffer.curBatchFrameCount();
int lastBatchSize = depth == 0 ? 0 : frameBuffer.currentBatchSize();
int nextBatchSize = batchSize(lastBatchSize);
if (isDebug) {
System.err.println("last batch size = " + lastBatchSize +
@ -312,19 +312,19 @@ final class StackStreamFactory {
* 2. reuse or expand the allocated buffers
* 3. create specialized StackFrame objects
*/
private Object doStackWalk(long anchor, int skipFrames, int batchSize,
int bufStartIndex, int bufEndIndex) {
private Object doStackWalk(long anchor, int skipFrames, int numFrames,
int bufStartIndex, int bufEndIndex) {
checkState(NEW);
frameBuffer.check(skipFrames);
if (isDebug) {
System.err.format("doStackWalk: skip %d start %d end %d%n",
skipFrames, bufStartIndex, bufEndIndex);
System.err.format("doStackWalk: skip %d start %d end %d nframes %d%n",
skipFrames, bufStartIndex, bufEndIndex, numFrames);
}
this.anchor = anchor; // set anchor for this bulk stack frame traversal
frameBuffer.setBatch(depth, bufStartIndex, bufEndIndex);
frameBuffer.setBatch(depth, bufStartIndex, numFrames);
// traverse all frames and perform the action on the stack frames, if specified
return consumeFrames();
@ -334,10 +334,8 @@ final class StackStreamFactory {
* Get next batch of stack frames.
*/
private int getNextBatch() {
int nextBatchSize = Math.min(maxDepth - depth, getNextBatchSize());
if (!frameBuffer.isActive()
|| (nextBatchSize <= 0)
|| (depth == maxDepth)
|| (frameBuffer.isAtBottom() && !hasMoreContinuations())) {
if (isDebug) {
System.out.format(" more stack walk done%n");
@ -346,11 +344,21 @@ final class StackStreamFactory {
return 0;
}
// VM ends the batch when it reaches the bottom of a continuation
// i.e. Continuation::enter. The stack walker will set the continuation
// to its parent to continue.
// Note that the current batch could have no stack frame filled. This could
// happen when Continuation::enter is the last element of the frame buffer
// filled in the last batch and it needs to fetch another batch in order to
// detect reaching the bottom.
if (frameBuffer.isAtBottom() && hasMoreContinuations()) {
if (isDebug) {
System.out.format(" set continuation to %s%n", continuation.getParent());
}
setContinuation(continuation.getParent());
}
int numFrames = fetchStackFrames(nextBatchSize);
int numFrames = fetchStackFrames();
if (numFrames == 0 && !hasMoreContinuations()) {
frameBuffer.freeze(); // done stack walking
}
@ -415,34 +423,35 @@ final class StackStreamFactory {
return callStackWalk(mode, 0,
contScope, continuation,
frameBuffer.curBatchFrameCount(),
frameBuffer.currentBatchSize(),
frameBuffer.startIndex(),
frameBuffer.frames());
}
/*
* Fetches stack frames.
* Fetches a new batch of stack frames. This method returns
* the number of stack frames filled in this batch.
*
* @param batchSize number of elements of the frame buffers for this batch
* @return number of frames fetched in this batch
* When it reaches the bottom of a continuation, i.e. Continuation::enter,
* VM ends the batch and let the stack walker to set the continuation
* to its parent and continue the stack walking. It may return zero.
*/
private int fetchStackFrames(int batchSize) {
private int fetchStackFrames() {
int startIndex = frameBuffer.startIndex();
frameBuffer.resize(startIndex, batchSize);
int endIndex = fetchStackFrames(mode, anchor, batchSize,
startIndex,
frameBuffer.frames());
// If the last batch didn't fetch any frames, keep the current batch size.
int lastBatchFrameCount = frameBuffer.numFrames();
int batchSize = getNextBatchSize();
frameBuffer.resize(batchSize);
int numFrames = fetchStackFrames(mode, anchor, lastBatchFrameCount,
batchSize, startIndex,
frameBuffer.frames());
if (isDebug) {
System.out.format(" more stack walk requesting %d got %d to %d frames%n",
batchSize, frameBuffer.startIndex(), endIndex);
}
int numFrames = endIndex - startIndex;
if (numFrames > 0) {
frameBuffer.setBatch(depth, startIndex, endIndex);
System.out.format(" more stack walk got %d frames start %d batch size %d%n",
numFrames, frameBuffer.startIndex(), batchSize);
}
frameBuffer.setBatch(depth, startIndex, numFrames);
return numFrames;
}
@ -454,7 +463,7 @@ final class StackStreamFactory {
* @param skipframes number of frames to be skipped before filling the frame buffer.
* @param contScope the continuation scope to walk.
* @param continuation the continuation to walk, or {@code null} if walking a thread.
* @param batchSize the batch size, max. number of elements to be filled in the frame buffers.
* @param bufferSize the buffer size
* @param startIndex start index of the frame buffers to be filled.
* @param frames Either a {@link ClassFrameInfo} array, if mode is {@link #CLASS_INFO_ONLY}
* or a {@link StackFrameInfo} (or derivative) array otherwise.
@ -462,7 +471,7 @@ final class StackStreamFactory {
*/
private native R callStackWalk(int mode, int skipframes,
ContinuationScope contScope, Continuation continuation,
int batchSize, int startIndex,
int bufferSize, int startIndex,
T[] frames);
/**
@ -470,15 +479,16 @@ final class StackStreamFactory {
*
* @param mode mode of stack walking
* @param anchor
* @param batchSize the batch size, max. number of elements to be filled in the frame buffers.
* @param lastBatchFrameCount the number of frames filled in the last batch.
* @param bufferSize the buffer size
* @param startIndex start index of the frame buffers to be filled.
* @param frames Either a {@link ClassFrameInfo} array, if mode is {@link #CLASS_INFO_ONLY}
* or a {@link StackFrameInfo} (or derivative) array otherwise.
*
* @return the end index to the frame buffers
* @return the number of frames filled in this batch
*/
private native int fetchStackFrames(int mode, long anchor,
int batchSize, int startIndex,
private native int fetchStackFrames(int mode, long anchor, int lastBatchFrameCount,
int bufferSize, int startIndex,
T[] frames);
private native void setContinuation(long anchor, T[] frames, Continuation cont);
@ -537,16 +547,18 @@ final class StackStreamFactory {
}
@Override
protected int batchSize(int lastBatchFrameCount) {
if (lastBatchFrameCount == 0) {
protected int batchSize(int lastBatchSize) {
if (lastBatchSize == 0) {
// First batch, use estimateDepth if not exceed the large batch size
int initialBatchSize = Math.max(walker.estimateDepth()+RESERVED_ELEMENTS, MIN_BATCH_SIZE);
return Math.min(initialBatchSize, LARGE_BATCH_SIZE);
} else {
if (lastBatchFrameCount > BATCH_SIZE) {
return lastBatchFrameCount;
// expand only if last batch was full and the buffer size <= 32
// to minimize the number of unneeded frames decoded.
if (lastBatchSize > BATCH_SIZE || !frameBuffer.isFull()) {
return lastBatchSize;
} else {
return Math.min(lastBatchFrameCount*2, BATCH_SIZE);
return Math.min(lastBatchSize*2, BATCH_SIZE);
}
}
}
@ -638,21 +650,20 @@ final class StackStreamFactory {
}
@Override
void resize(int startIndex, int elements) {
void resize(int size) {
if (!isActive())
throw new IllegalStateException("inactive frame buffer can't be resized");
assert startIndex == START_POS :
"bad start index " + startIndex + " expected " + START_POS;
assert startIndex() == START_POS :
"bad start index " + startIndex() + " expected " + START_POS;
int size = startIndex+elements;
if (stackFrames.length < size) {
T[] newFrames = allocateArray(size);
// copy initial magic...
System.arraycopy(stackFrames, 0, newFrames, 0, startIndex);
System.arraycopy(stackFrames, 0, newFrames, 0, startIndex());
stackFrames = newFrames;
}
fill(stackFrames, startIndex, size);
fill(stackFrames, startIndex(), size);
currentBatchSize = size;
}
@ -762,7 +773,7 @@ final class StackStreamFactory {
}
@Override
protected int batchSize(int lastBatchFrameCount) {
protected int batchSize(int lastBatchSize) {
// this method is only called when the caller class is not found in
// the first batch. getCallerClass may be invoked via core reflection.
// So increase the next batch size as there may be implementation-specific
@ -803,8 +814,7 @@ final class StackStreamFactory {
// buffers for VM to fill stack frame info
int currentBatchSize; // current batch size
int origin; // index to the current traversed stack frame
int fence; // index to the last frame in the current batch
int fence; // index past the last frame of the current batch
FrameBuffer(int initialBatchSize) {
if (initialBatchSize < MIN_BATCH_SIZE) {
throw new IllegalArgumentException(initialBatchSize +
@ -830,16 +840,13 @@ final class StackStreamFactory {
/**
* Resizes the buffers for VM to fill in the next batch of stack frames.
* The next batch will start at the given startIndex with the maximum number
* of elements.
*
* <p> Subclass may override this method to manage the allocated buffers.
*
* @param startIndex the start index for the first frame of the next batch to fill in.
* @param elements the number of elements for the next batch to fill in.
* @param size new batch size
*
*/
abstract void resize(int startIndex, int elements);
abstract void resize(int size);
/**
* Return the class at the given position in the current batch.
@ -871,8 +878,8 @@ final class StackStreamFactory {
// ------ FrameBuffer implementation ------
final int curBatchFrameCount() {
return currentBatchSize-START_POS;
final int currentBatchSize() {
return currentBatchSize;
}
/*
@ -882,6 +889,15 @@ final class StackStreamFactory {
return origin >= fence || (origin == START_POS && fence == 0);
}
/*
* Returns the number of stack frames filled in the current batch
*/
final int numFrames() {
if (!isActive())
throw new IllegalStateException();
return fence - startIndex();
}
/*
* Freezes this frame buffer. The stack stream source is done fetching.
*/
@ -892,10 +908,14 @@ final class StackStreamFactory {
/*
* Tests if this frame buffer is active. It is inactive when
* it is done for traversal. All stack frames have been traversed.
* it is done for traversal.
*/
final boolean isActive() {
return origin > 0; // && (fence == 0 || origin < fence || fence == currentBatchSize);
return origin > 0;
}
final boolean isFull() {
return fence == currentBatchSize;
}
/*
@ -918,7 +938,7 @@ final class StackStreamFactory {
if (isDebug) {
int index = origin-1;
System.out.format(" next frame at %d: %s (origin %d fence %d)%n", index,
Objects.toString(c), index, fence);
c.getName(), index, fence);
}
return c;
}
@ -941,17 +961,16 @@ final class StackStreamFactory {
}
/*
* Set the start and end index of a new batch of stack frames that have
* been filled in this frame buffer.
* Set a new batch of stack frames that have been filled in this frame buffer.
*/
final void setBatch(int depth, int startIndex, int endIndex) {
if (startIndex <= 0 || endIndex <= 0)
final void setBatch(int depth, int startIndex, int numFrames) {
if (startIndex <= 0 || numFrames < 0)
throw new IllegalArgumentException("startIndex=" + startIndex
+ " endIndex=" + endIndex);
+ " numFrames=" + numFrames);
this.origin = startIndex;
this.fence = endIndex;
for (int i = START_POS; i < fence; i++) {
this.fence = startIndex + numFrames;
for (int i = startIndex; i < fence; i++) {
if (isDebug) System.err.format(" frame %d: %s%n", i, at(i));
if (depth == 0 && filterStackWalkImpl(at(i))) { // filter the frames due to the stack stream implementation
origin++;