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The following commit(s) were added to refs/heads/main by this push:
     new 2538f6d  Fix problems with file uploads and HTTP/2
2538f6d is described below

commit 2538f6d74949751901afc5e04014ede4f867152a
Author: Mark Thomas <ma...@apache.org>
AuthorDate: Mon Jun 14 21:15:30 2021 +0100

    Fix problems with file uploads and HTTP/2
    
    Small writes from the user agent were triggering small window updates
    which in turn triggered more small writes. With lots of small writes the
    overhead protection code was activated and the connection closed.
---
 .../coyote/http2/Http2AsyncUpgradeHandler.java     | 30 ++++++++++++-------
 .../apache/coyote/http2/Http2UpgradeHandler.java   | 34 +++++++++++++++-------
 .../apache/coyote/http2/LocalStrings.properties    |  2 ++
 java/org/apache/coyote/http2/Stream.java           | 24 +++++++++++++++
 webapps/docs/changelog.xml                         | 10 +++++++
 5 files changed, 79 insertions(+), 21 deletions(-)

diff --git a/java/org/apache/coyote/http2/Http2AsyncUpgradeHandler.java 
b/java/org/apache/coyote/http2/Http2AsyncUpgradeHandler.java
index b77fee6..6d7e3eb 100644
--- a/java/org/apache/coyote/http2/Http2AsyncUpgradeHandler.java
+++ b/java/org/apache/coyote/http2/Http2AsyncUpgradeHandler.java
@@ -231,22 +231,32 @@ public class Http2AsyncUpgradeHandler extends 
Http2UpgradeHandler {
     @Override
     void writeWindowUpdate(AbstractNonZeroStream stream, int increment, 
boolean applicationInitiated)
             throws IOException {
+        if (log.isDebugEnabled()) {
+            log.debug(sm.getString("upgradeHandler.windowUpdateConnection",
+                    getConnectionId(), Integer.valueOf(increment)));
+        }
         // Build window update frame for stream 0
         byte[] frame = new byte[13];
         ByteUtil.setThreeBytes(frame, 0,  4);
         frame[3] = FrameType.WINDOW_UPDATE.getIdByte();
         ByteUtil.set31Bits(frame, 9, increment);
         // No need to send update from closed stream
-        if  (stream instanceof Stream && ((Stream) stream).canWrite()) {
-            // Change stream Id
-            byte[] frame2 = new byte[13];
-            ByteUtil.setThreeBytes(frame2, 0,  4);
-            frame2[3] = FrameType.WINDOW_UPDATE.getIdByte();
-            ByteUtil.set31Bits(frame2, 9, increment);
-            ByteUtil.set31Bits(frame2, 5, stream.getIdAsInt());
-            socketWrapper.write(BlockingMode.SEMI_BLOCK, 
protocol.getWriteTimeout(),
-                    TimeUnit.MILLISECONDS, null, 
SocketWrapperBase.COMPLETE_WRITE, errorCompletion,
-                    ByteBuffer.wrap(frame), ByteBuffer.wrap(frame2));
+        if (stream instanceof Stream && ((Stream) stream).canWrite()) {
+            int streamIncrement = ((Stream) 
stream).getWindowUpdateSizeToWrite(increment);
+            if (streamIncrement > 0) {
+                if (log.isDebugEnabled()) {
+                    log.debug(sm.getString("upgradeHandler.windowUpdateStream",
+                            getConnectionId(), getIdAsString(), 
Integer.valueOf(streamIncrement)));
+                }
+                byte[] frame2 = new byte[13];
+                ByteUtil.setThreeBytes(frame2, 0,  4);
+                frame2[3] = FrameType.WINDOW_UPDATE.getIdByte();
+                ByteUtil.set31Bits(frame2, 9, streamIncrement);
+                ByteUtil.set31Bits(frame2, 5, stream.getIdAsInt());
+                socketWrapper.write(BlockingMode.SEMI_BLOCK, 
protocol.getWriteTimeout(),
+                        TimeUnit.MILLISECONDS, null, 
SocketWrapperBase.COMPLETE_WRITE, errorCompletion,
+                        ByteBuffer.wrap(frame), ByteBuffer.wrap(frame2));
+            }
         } else {
             socketWrapper.write(BlockingMode.SEMI_BLOCK, 
protocol.getWriteTimeout(),
                     TimeUnit.MILLISECONDS, null, 
SocketWrapperBase.COMPLETE_WRITE, errorCompletion,
diff --git a/java/org/apache/coyote/http2/Http2UpgradeHandler.java 
b/java/org/apache/coyote/http2/Http2UpgradeHandler.java
index 994a7cb..fa650b7 100644
--- a/java/org/apache/coyote/http2/Http2UpgradeHandler.java
+++ b/java/org/apache/coyote/http2/Http2UpgradeHandler.java
@@ -804,6 +804,10 @@ class Http2UpgradeHandler extends AbstractStream 
implements InternalHttpUpgradeH
      */
     void writeWindowUpdate(AbstractNonZeroStream stream, int increment, 
boolean applicationInitiated)
             throws IOException {
+        if (log.isDebugEnabled()) {
+            log.debug(sm.getString("upgradeHandler.windowUpdateConnection",
+                    getConnectionId(), Integer.valueOf(increment)));
+        }
         synchronized (socketWrapper) {
             // Build window update frame for stream 0
             byte[] frame = new byte[13];
@@ -812,17 +816,25 @@ class Http2UpgradeHandler extends AbstractStream 
implements InternalHttpUpgradeH
             ByteUtil.set31Bits(frame, 9, increment);
             socketWrapper.write(true, frame, 0, frame.length);
             // No need to send update from closed stream
-            if  (stream instanceof Stream && ((Stream) stream).canWrite()) {
-                // Change stream Id and re-use
-                ByteUtil.set31Bits(frame, 5, stream.getIdAsInt());
-                try {
-                    socketWrapper.write(true, frame, 0, frame.length);
-                    socketWrapper.flush(true);
-                } catch (IOException ioe) {
-                    if (applicationInitiated) {
-                        handleAppInitiatedIOException(ioe);
-                    } else {
-                        throw ioe;
+            if (stream instanceof Stream && ((Stream) stream).canWrite()) {
+                int streamIncrement = ((Stream) 
stream).getWindowUpdateSizeToWrite(increment);
+                if (streamIncrement > 0) {
+                    if (log.isDebugEnabled()) {
+                        
log.debug(sm.getString("upgradeHandler.windowUpdateStream",
+                                getConnectionId(), getIdAsString(), 
Integer.valueOf(streamIncrement)));
+                    }
+                    // Re-use buffer as connection update has already been 
written
+                    ByteUtil.set31Bits(frame, 5, stream.getIdAsInt());
+                    ByteUtil.set31Bits(frame, 9, streamIncrement);
+                    try {
+                        socketWrapper.write(true, frame, 0, frame.length);
+                        socketWrapper.flush(true);
+                    } catch (IOException ioe) {
+                        if (applicationInitiated) {
+                            handleAppInitiatedIOException(ioe);
+                        } else {
+                            throw ioe;
+                        }
                     }
                 }
             } else {
diff --git a/java/org/apache/coyote/http2/LocalStrings.properties 
b/java/org/apache/coyote/http2/LocalStrings.properties
index 3e114d8..25858cb 100644
--- a/java/org/apache/coyote/http2/LocalStrings.properties
+++ b/java/org/apache/coyote/http2/LocalStrings.properties
@@ -158,6 +158,8 @@ upgradeHandler.upgradeDispatch.entry=Entry, Connection 
[{0}], SocketStatus [{1}]
 upgradeHandler.upgradeDispatch.exit=Exit, Connection [{0}], SocketState [{1}]
 upgradeHandler.windowSizeReservationInterrupted=Connection [{0}], Stream 
[{1}], reservation for [{2}] bytes
 upgradeHandler.windowSizeTooBig=Connection [{0}], Stream [{1}], Window size 
too big
+upgradeHandler.windowUpdateConnection=Connection [{0}], Sent window update to 
client increasing window by [{1}] bytes
+upgradeHandler.windowUpdateStream=Connection [{0}], Stream [{1}], Sent window 
update to client increasing window by [{2}] bytes
 upgradeHandler.writeBody=Connection [{0}], Stream [{1}], Data length [{2}], 
EndOfStream [{3}]
 upgradeHandler.writeHeaders=Connection [{0}], Stream [{1}], Writing the 
headers, EndOfStream [{2}]
 upgradeHandler.writePushHeaders=Connection [{0}], Stream [{1}], Pushed stream 
[{2}], EndOfStream [{3}]
diff --git a/java/org/apache/coyote/http2/Stream.java 
b/java/org/apache/coyote/http2/Stream.java
index 28ec14e..8d93d98 100644
--- a/java/org/apache/coyote/http2/Stream.java
+++ b/java/org/apache/coyote/http2/Stream.java
@@ -82,6 +82,9 @@ class Stream extends AbstractNonZeroStream implements 
HeaderEmitter {
 
     private volatile StringBuilder cookieHeader = null;
 
+    private Object pendingWindowUpdateForStreamLock = new Object();
+    private int pendingWindowUpdateForStream = 0;
+
 
     Stream(Integer identifier, Http2UpgradeHandler handler) {
         this(identifier, handler, null);
@@ -744,6 +747,27 @@ class Stream extends AbstractNonZeroStream implements 
HeaderEmitter {
     }
 
 
+    int getWindowUpdateSizeToWrite(int increment) {
+        int result;
+        int threshold = 
handler.getProtocol().getOverheadWindowUpdateThreshold();
+        synchronized (pendingWindowUpdateForStreamLock) {
+            if (increment > threshold) {
+                result = increment + pendingWindowUpdateForStream;
+                pendingWindowUpdateForStream = 0;
+            } else {
+                pendingWindowUpdateForStream += increment;
+                if (pendingWindowUpdateForStream > threshold) {
+                    result = pendingWindowUpdateForStream;
+                    pendingWindowUpdateForStream = 0;
+                } else {
+                    result = 0;
+                }
+            }
+        }
+        return result;
+    }
+
+
     private static void push(final Http2UpgradeHandler handler, final Request 
request,
             final Stream stream) throws IOException {
         if (org.apache.coyote.Constants.IS_SECURITY_ENABLED) {
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 41ebbd0..c5dc156 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -112,6 +112,16 @@
         connections. Treat them the same way as clean closes of non-TLS
         connections rather than as unknown errors. (markt)
       </fix>
+      <fix>
+        Modify the HTTP/2 connector not to sent small updates for stream flow
+        control windows to the user agent as, depending on how the user agent 
is
+        written, this may trigger small writes from the user agent that in turn
+        trigger the overhead protection. Small updates for stream flow control
+        windows are now combined with subsequent flow control window updates 
for
+        that stream to ensure that all stream flow control window updates sent
+        from Tomcat are larger than <code>overheadWindowUpdateThreshold</code>.
+        (markt)
+      </fix>
     </changelog>
   </subsection>
   <subsection name="Other">

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