https://bz.apache.org/bugzilla/show_bug.cgi?id=58659
Bug ID: 58659
Summary: Http2Parser.readFrame() hanging on an unconditional
blocking read is necessary (TestHttp2Section_5_3 test)
Product: Tomcat 9
Version: 9.0.0.M1
Hardware: PC
Status: NEW
Severity: normal
Priority: P2
Component: Catalina
Assignee: dev@tomcat.apache.org
Reporter: knst.koli...@gmail.com
Trunk at revision 1716783
Buildbot run:
https://ci.apache.org/builders/tomcat-trunk/builds/690
Log file:
https://ci.apache.org/projects/tomcat/tomcat9/logs/logs/1716783/TEST-org.apache.coyote.http2.TestHttp2Section_5_3.NIO.txt
In TestHttp2Section_5_3.java there is a comment on lines 127-144:
// The loop below handles 0, 1 or 2 stream being blocked
<...>
// - If 2 streams are blocked the connection window will be set to one
// but one byte will be permitted for both streams (due to rounding in
// the allocation). The window size should be -1 (see below). Two
// frames (one for each stream will be written) one of which will be
// consumed by the client. The loop will start again and the Window
// size incremented to zero. No data will be written by the streams
// but the second data frame written in the last iteration of the loop
// will be read. The loop will then exit since frames from both
// streams will have been observed.
The sequence of events in while(!seen19 || !seen21) loop (line 147) on this
test run was:
iteration 1: a body of stream 21 was read ("21-Body-1")
iteration 2: "parser.readFrame(true);" call blocks until it times out after
waiting for 30 seconds
[[[
Testcase: testWeighting took 35.576 sec
Caused an ERROR
Read timed out
java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:170)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at
org.apache.coyote.http2.Http2TestBase$TestInput.fill(Http2TestBase.java:720)
at org.apache.coyote.http2.Http2Parser$Input.fill(Http2Parser.java:565)
at org.apache.coyote.http2.Http2Parser.readFrame(Http2Parser.java:75)
at org.apache.coyote.http2.Http2Parser.readFrame(Http2Parser.java:68)
at
org.apache.coyote.http2.TestHttp2Section_5_3.testWeighting(TestHttp2Section_5_3.java:149)
]]]
My concern is implementation of Http2Parser.readFrame() method.
It starts with unconditionally calling "input.fill(block, frameHeaderBuffer)"
regardless of whether the frame bytes have already been read. I think it shall
check whether the blocking read is necessary or if enough the data have already
been received.
The comment that I cited says "but the second data frame written in the last
iteration of the loop will be read". I think that because of unconditional call
to input.fill() the thread will block reading for data, regardless of whether
the second data frame has already been received.
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