[trafficserver] branch master updated: new_MIOBuffer: uninitialized water_mark fix.

[zw...@apache.org]

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zwoop pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/trafficserver.git


The following commit(s) were added to refs/heads/master by this push:
     new db81103  new_MIOBuffer: uninitialized water_mark fix.
db81103 is described below

commit db81103d05efb94d72f5da953388eff08916db17
Author: Gancho Tenev <ga...@apache.org>
AuthorDate: Thu Jan 11 21:35:18 2018 -0800

    new_MIOBuffer: uninitialized water_mark fix.
    
    While calling new_MIOBuffer() the water_mark is not initialized,
    water_mark could end up with a very high (random) value to be used
    during the network reads. This always results in overly aggressive
    uninterrupted reading from the connection, severe buffer size increase
    and CPU saturation of one or more ET_NET threads which renders the
    traffic server unresponsive. Initializing the water_mark fixes the issue.
    
    The problem can be easily reproduced by a series of very large TLS POST
    requests in combination with a stalling origin server and periodic use
    of FetchSM which internally allocates a buffer using new_MIOBuffer()
    and sets water_mark to INT64_MAX.
    While serving the POST requests a buffer previously used by FetchSM
    would be reused and its water_mark would end up being equal to IN64_MAX
    since the water mark is not initialized when calling new_MIOBuffer().
    This always results in aggressive uninterrupted network reads, the
    buffer size keep growing progressively and the constant block iteration
    in IOBufferReader::read_avail() at some point would saturate the ET_NET
    thread CPU.
    
    This patch should fix issue #2144
    
    Additionally fixed erroneous #ifdef TS_USE_PORT directive in
    SSLNetVConnection::net_read_io().
---
 iocore/eventsystem/P_IOBuffer.h | 1 +
 iocore/net/SSLNetVConnection.cc | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/iocore/eventsystem/P_IOBuffer.h b/iocore/eventsystem/P_IOBuffer.h
index dc29937..748811c 100644
--- a/iocore/eventsystem/P_IOBuffer.h
+++ b/iocore/eventsystem/P_IOBuffer.h
@@ -1123,6 +1123,7 @@ MIOBuffer::alloc(int64_t i)
 #endif
   _writer->alloc(i);
   size_index = i;
+  water_mark = 0;
   init_readers();
 }
 
diff --git a/iocore/net/SSLNetVConnection.cc b/iocore/net/SSLNetVConnection.cc
index f3f2f09..9c2a513 100644
--- a/iocore/net/SSLNetVConnection.cc
+++ b/iocore/net/SSLNetVConnection.cc
@@ -625,7 +625,7 @@ SSLNetVConnection::net_read_io(NetHandler *nh, EThread *lthread)
     read.triggered = 0;
     nh->read_ready_list.remove(this);
     Debug("ssl", "read_from_net, read finished - would block");
-#ifdef TS_USE_PORT
+#if TS_USE_PORT
     if (ret == SSL_READ_WOULD_BLOCK) {
       readReschedule(nh);
     } else {

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