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Re: a lot of TCP_SWAPFAIL_MISS/200

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On 19/07/2015 10:09 p.m., HackXBack wrote:
> but this happen only with version 3.5 , and it increase after restarting
> squid or rebooting system
> this is bug in 3.5 and it decrease the HIT ratio ,
> you dont think so ? 

I've seen a lot of reports of it happening on all Squid versions where
shutdown did not properly finished saving to those cache files. Usually
gets bad with very short configured shutdown_lifetime values. Although
it can happen anytime shutdown interrupts a busy set of clients.

FYI: attached is a backport of a Squid-4 change which should reduce that
shutdown situation being a problem. If you would like to test we can see
if it helps with your case.


SWAPFAIL also gets seen a lot on caches (or individual files) that were
created by very old Squid versions (older than 3.1 or 3.3 IIRC) before
we added checksum validation. Those old objects metadata fail the
checksum due to format differences at the bit level and SWAPFAIL is done
to replace them with guaranteed clean content.

The same checksum fails can also still happen on objects created with a
32-bit Squid loaded by a 64-bit Squid, and vice-versa. For the same reasons.

Then there is genuine HDD corruption, mutiple Squid processes or workers
touching each others cache files, etc. other programs touching them etc.

So many causes it is guesswork. But an educated guess says it is
shutdown related errors.

Amos

=== modified file 'src/base/RunnersRegistry.cc'
--- src/base/RunnersRegistry.cc	2015-01-13 09:13:49 +0000
+++ src/base/RunnersRegistry.cc	2015-07-19 15:08:16 +0000
@@ -15,40 +15,48 @@
 /// all known runners
 static Runners *TheRunners = NULL;
 
 /// safely returns registered runners, initializing structures as needed
 static Runners &
 GetRunners()
 {
     if (!TheRunners)
         TheRunners = new Runners;
     return *TheRunners;
 }
 
 int
 RegisterRunner(RegisteredRunner *rr)
 {
     Runners &runners = GetRunners();
     runners.insert(rr);
     return runners.size();
 }
 
+int
+DeregisterRunner(RegisteredRunner *rr)
+{
+    Runners &runners = GetRunners();
+    runners.erase(rr);
+    return runners.size();
+}
+
 void
 RunRegistered(const RegisteredRunner::Method &m)
 {
     Runners &runners = GetRunners();
     typedef Runners::iterator RRI;
     for (RRI i = runners.begin(); i != runners.end(); ++i)
         ((*i)->*m)();
 
     if (m == &RegisteredRunner::finishShutdown) {
         delete TheRunners;
         TheRunners = NULL;
     }
 }
 
 bool
 UseThisStatic(const void *)
 {
     return true;
 }
 

=== modified file 'src/base/RunnersRegistry.h'
--- src/base/RunnersRegistry.h	2015-01-13 09:13:49 +0000
+++ src/base/RunnersRegistry.h	2015-07-19 15:08:16 +0000
@@ -51,54 +51,63 @@
     virtual void claimMemoryNeeds() {}
 
     /// Called after claimMemoryNeeds().
     /// Meant for activating modules and features using a finalized
     /// configuration with known memory requirements.
     virtual void useConfig() {}
 
     /* Reconfiguration events */
 
     /// Called after parsing squid.conf during reconfiguration.
     /// Meant for adjusting the module state based on configuration changes.
     virtual void syncConfig() {}
 
     /* Shutdown events */
 
     /// Called after receiving a shutdown request and before stopping the main
     /// loop. At least one main loop iteration is guaranteed after this call.
     /// Meant for cleanup and state saving that may require other modules.
     virtual void startShutdown() {}
 
+    /// Called after shutdown_lifetime grace period ends and before stopping
+    /// the main loop. At least one main loop iteration is guaranteed after
+    /// this call.
+    /// Meant for cleanup and state saving that may require other modules.
+    virtual void endingShutdown() {}
+
     /// Called after stopping the main loop and before releasing memory.
     /// Meant for quick/basic cleanup that does not require any other modules.
     virtual ~RegisteredRunner() {}
     /// exists to simplify caller interface; override the destructor instead
     void finishShutdown() { delete this; }
 
     /// a pointer to one of the above notification methods
     typedef void (RegisteredRunner::*Method)();
 
 };
 
 /// registers a given runner with the given registry and returns registry count
 int RegisterRunner(RegisteredRunner *rr);
 
+/// de-registers a given runner with the given registry and returns registry count
+int DeregisterRunner(RegisteredRunner *rr);
+
 /// Calls a given method of all runners.
 /// All runners are destroyed after the finishShutdown() call.
 void RunRegistered(const RegisteredRunner::Method &m);
 
 /// convenience macro to describe/debug the caller and the method being called
 #define RunRegisteredHere(m) \
     debugs(1, 2, "running " # m); \
     RunRegistered(&m)
 
 /// convenience function to "use" an otherwise unreferenced static variable
 bool UseThisStatic(const void *);
 
 /// convenience macro: register one RegisteredRunner kid as early as possible
 #define RunnerRegistrationEntry(Who) \
     static const bool Who ## _Registered_ = \
         RegisterRunner(new Who) > 0 && \
         UseThisStatic(& Who ## _Registered_);
 
 #endif /* SQUID_BASE_RUNNERSREGISTRY_H */
 

=== modified file 'src/client_side.cc'
--- src/client_side.cc	2015-06-05 23:41:22 +0000
+++ src/client_side.cc	2015-07-19 15:08:16 +0000
@@ -797,40 +797,41 @@
     if (aur != auth_) {
         debugs(33, 2, "ERROR: Closing " << clientConnection << " due to change of connection-auth from " << by);
         auth_->releaseAuthServer();
         auth_ = NULL;
         // this is a fatal type of problem.
         // Close the connection immediately with TCP RST to abort all traffic flow
         comm_reset_close(clientConnection);
         return;
     }
 
     /* NOT REACHABLE */
 }
 #endif
 
 // cleans up before destructor is called
 void
 ConnStateData::swanSong()
 {
     debugs(33, 2, HERE << clientConnection);
     flags.readMore = false;
+    DeregisterRunner(this);
     clientdbEstablished(clientConnection->remote, -1);  /* decrement */
     assert(areAllContextsForThisConnection());
     freeAllContexts();
 
     unpinConnection(true);
 
     if (Comm::IsConnOpen(clientConnection))
         clientConnection->close();
 
 #if USE_AUTH
     // NP: do this bit after closing the connections to avoid side effects from unwanted TCP RST
     setAuth(NULL, "ConnStateData::SwanSong cleanup");
 #endif
 
     BodyProducer::swanSong();
     flags.swanSang = true;
 }
 
 bool
 ConnStateData::isOpen() const
@@ -1874,40 +1875,66 @@
     }
 }
 
 ClientSocketContext *
 ConnStateData::abortRequestParsing(const char *const uri)
 {
     ClientHttpRequest *http = new ClientHttpRequest(this);
     http->req_sz = in.buf.length();
     http->uri = xstrdup(uri);
     setLogUri (http, uri);
     ClientSocketContext *context = new ClientSocketContext(clientConnection, http);
     StoreIOBuffer tempBuffer;
     tempBuffer.data = context->reqbuf;
     tempBuffer.length = HTTP_REQBUF_SZ;
     clientStreamInit(&http->client_stream, clientGetMoreData, clientReplyDetach,
                      clientReplyStatus, new clientReplyContext(http), clientSocketRecipient,
                      clientSocketDetach, context, tempBuffer);
     return context;
 }
 
+void
+ConnStateData::startShutdown()
+{
+    // RegisteredRunner API callback - Squid has been shut down
+
+    // if connection is idle terminate it now,
+    // otherwise wait for grace period to end
+    if (getConcurrentRequestCount() == 0)
+        endingShutdown();
+}
+
+void
+ConnStateData::endingShutdown()
+{
+    // RegisteredRunner API callback - Squid shutdown grace period is over
+
+    // force the client connection to close immediately
+    // swanSong() in the close handler will cleanup.
+    if (Comm::IsConnOpen(clientConnection))
+        clientConnection->close();
+
+    // deregister now to ensure finalShutdown() does not kill us prematurely.
+    // fd_table purge will cleanup if close handler was not fast enough.
+    DeregisterRunner(this);
+}
+
 char *
 skipLeadingSpace(char *aString)
 {
     char *result = aString;
 
     while (xisspace(*aString))
         ++aString;
 
     return result;
 }
 
 /**
  * 'end' defaults to NULL for backwards compatibility
  * remove default value if we ever get rid of NULL-terminated
  * request buffers.
  */
 const char *
 findTrailingHTTPVersion(const char *uriAndHTTPVersion, const char *end)
 {
     if (NULL == end) {
@@ -3502,40 +3529,44 @@
     signAlgorithm(Ssl::algSignTrusted),
 #endif
     stoppedSending_(NULL),
     stoppedReceiving_(NULL)
 {
     flags.readMore = true; // kids may overwrite
     flags.swanSang = false;
 
     pinning.host = NULL;
     pinning.port = -1;
     pinning.pinned = false;
     pinning.auth = false;
     pinning.zeroReply = false;
     pinning.peer = NULL;
 
     // store the details required for creating more MasterXaction objects as new requests come in
     clientConnection = xact->tcpClient;
     port = xact->squidPort;
     log_addr = xact->tcpClient->remote;
     log_addr.applyMask(Config.Addrs.client_netmask);
+
+    // register to receive notice of Squid signal events
+    // which may affect long persisting client connections
+    RegisterRunner(this);
 }
 
 void
 ConnStateData::start()
 {
     BodyProducer::start();
     HttpControlMsgSink::start();
 
     if (port->disable_pmtu_discovery != DISABLE_PMTU_OFF &&
             (transparent() || port->disable_pmtu_discovery == DISABLE_PMTU_ALWAYS)) {
 #if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
         int i = IP_PMTUDISC_DONT;
         if (setsockopt(clientConnection->fd, SOL_IP, IP_MTU_DISCOVER, &i, sizeof(i)) < 0)
             debugs(33, 2, "WARNING: Path MTU discovery disabling failed on " << clientConnection << " : " << xstrerror());
 #else
         static bool reported = false;
 
         if (!reported) {
             debugs(33, DBG_IMPORTANT, "NOTICE: Path MTU discovery disabling is not supported on your platform.");
             reported = true;

=== modified file 'src/client_side.h'
--- src/client_side.h	2015-04-13 05:59:05 +0000
+++ src/client_side.h	2015-07-19 15:08:41 +0000
@@ -1,33 +1,34 @@
 /*
  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
  *
  * Squid software is distributed under GPLv2+ license and includes
  * contributions from numerous individuals and organizations.
  * Please see the COPYING and CONTRIBUTORS files for details.
  */
 
 /* DEBUG: section 33    Client-side Routines */
 
 #ifndef SQUID_CLIENTSIDE_H
 #define SQUID_CLIENTSIDE_H
 
+#include "base/RunnersRegistry.h"
 #include "clientStreamForward.h"
 #include "comm.h"
 #include "helper/forward.h"
 #include "HttpControlMsg.h"
 #include "HttpParser.h"
 #include "ipc/FdNotes.h"
 #include "SBuf.h"
 #if USE_AUTH
 #include "auth/UserRequest.h"
 #endif
 #if USE_OPENSSL
 #include "ssl/support.h"
 #endif
 
 class ConnStateData;
 class ClientHttpRequest;
 class clientStreamNode;
 class ChunkedCodingParser;
 namespace AnyP
 {
@@ -152,41 +153,41 @@
 #if USE_OPENSSL
 namespace Ssl
 {
 class ServerBump;
 }
 #endif
 /**
  * Manages a connection to a client.
  *
  * Multiple requests (up to pipeline_prefetch) can be pipelined. This object is responsible for managing
  * which one is currently being fulfilled and what happens to the queue if the current one
  * causes the client connection to be closed early.
  *
  * Act as a manager for the connection and passes data in buffer to the current parser.
  * the parser has ambiguous scope at present due to being made from global functions
  * I believe this object uses the parser to identify boundaries and kick off the
  * actual HTTP request handling objects (ClientSocketContext, ClientHttpRequest, HttpRequest)
  *
  * If the above can be confirmed accurate we can call this object PipelineManager or similar
  */
-class ConnStateData : public BodyProducer, public HttpControlMsgSink
+class ConnStateData : public BodyProducer, public HttpControlMsgSink, public RegisteredRunner
 {
 
 public:
     explicit ConnStateData(const MasterXaction::Pointer &xact);
     virtual ~ConnStateData();
 
     void readSomeData();
     bool areAllContextsForThisConnection() const;
     void freeAllContexts();
     void notifyAllContexts(const int xerrno); ///< tell everybody about the err
     /// Traffic parsing
     bool clientParseRequests();
     void readNextRequest();
     ClientSocketContext::Pointer getCurrentContext() const;
     void addContextToQueue(ClientSocketContext * context);
     int getConcurrentRequestCount() const;
     bool isOpen() const;
 
     // HttpControlMsgSink API
     virtual void sendControlMsg(HttpControlMsg msg);
@@ -382,40 +383,44 @@
 
     /* clt_conn_tag=tag annotation access */
     const SBuf &connectionTag() const { return connectionTag_; }
     void connectionTag(const char *aTag) { connectionTag_ = aTag; }
 
     /// handle a control message received by context from a peer and call back
     virtual void writeControlMsgAndCall(ClientSocketContext *context, HttpReply *rep, AsyncCall::Pointer &call) = 0;
 
     /// ClientStream calls this to supply response header (once) and data
     /// for the current ClientSocketContext.
     virtual void handleReply(HttpReply *header, StoreIOBuffer receivedData) = 0;
 
     /// remove no longer needed leading bytes from the input buffer
     void consumeInput(const size_t byteCount);
 
     /* TODO: Make the methods below (at least) non-public when possible. */
 
     /// stop parsing the request and create context for relaying error info
     ClientSocketContext *abortRequestParsing(const char *const errUri);
 
+    /* Registered Runner API */
+    virtual void startShutdown();
+    virtual void endingShutdown();
+
 protected:
     void startDechunkingRequest();
     void finishDechunkingRequest(bool withSuccess);
     void abortChunkedRequestBody(const err_type error);
     err_type handleChunkedRequestBody(size_t &putSize);
 
     void startPinnedConnectionMonitoring();
     void clientPinnedConnectionRead(const CommIoCbParams &io);
 
     /// parse input buffer prefix into a single transfer protocol request
     /// return NULL to request more header bytes (after checking any limits)
     /// use abortRequestParsing() to handle parsing errors w/o creating request
     virtual ClientSocketContext *parseOneRequest(Http::ProtocolVersion &ver) = 0;
 
     /// start processing a freshly parsed request
     virtual void processParsedRequest(ClientSocketContext *context, const Http::ProtocolVersion &ver) = 0;
 
     /// returning N allows a pipeline of 1+N requests (see pipeline_prefetch)
     virtual int pipelinePrefetchMax() const;
 

=== modified file 'src/main.cc'
--- src/main.cc	2015-03-21 08:16:46 +0000
+++ src/main.cc	2015-07-19 15:11:12 +0000
@@ -186,40 +186,52 @@
 
 public:
     int checkEvents(int timeout) {
         Store::Root().callback();
         return EVENT_IDLE;
     };
 };
 
 class SignalEngine: public AsyncEngine
 {
 
 public:
     virtual int checkEvents(int timeout);
 
 private:
     static void StopEventLoop(void *) {
         if (EventLoop::Running)
             EventLoop::Running->stop();
     }
 
+    static void FinalShutdownRunners(void *) {
+        RunRegisteredHere(RegisteredRunner::endingShutdown);
+
+        // XXX: this should be a Runner.
+#if USE_AUTH
+        /* detach the auth components (only do this on full shutdown) */
+        Auth::Scheme::FreeAll();
+#endif
+
+        eventAdd("SquidTerminate", &StopEventLoop, NULL, 0, 1, false);
+    }
+
     void doShutdown(time_t wait);
 };
 
 int
 SignalEngine::checkEvents(int timeout)
 {
     PROF_start(SignalEngine_checkEvents);
 
     if (do_reconfigure) {
         mainReconfigureStart();
         do_reconfigure = 0;
     } else if (do_rotate) {
         mainRotate();
         do_rotate = 0;
     } else if (do_shutdown) {
         doShutdown(do_shutdown > 0 ? (int) Config.shutdownLifetime : 0);
         do_shutdown = 0;
     }
     BroadcastSignalIfAny(DebugSignal);
     BroadcastSignalIfAny(RotateSignal);
@@ -227,47 +239,42 @@
     BroadcastSignalIfAny(ShutdownSignal);
 
     PROF_stop(SignalEngine_checkEvents);
     return EVENT_IDLE;
 }
 
 void
 SignalEngine::doShutdown(time_t wait)
 {
     debugs(1, DBG_IMPORTANT, "Preparing for shutdown after " << statCounter.client_http.requests << " requests");
     debugs(1, DBG_IMPORTANT, "Waiting " << wait << " seconds for active connections to finish");
 
     shutting_down = 1;
 
 #if USE_WIN32_SERVICE
     WIN32_svcstatusupdate(SERVICE_STOP_PENDING, (wait + 1) * 1000);
 #endif
 
     /* run the closure code which can be shared with reconfigure */
     serverConnectionsClose();
-#if USE_AUTH
-    /* detach the auth components (only do this on full shutdown) */
-    Auth::Scheme::FreeAll();
-#endif
-
     RunRegisteredHere(RegisteredRunner::startShutdown);
-    eventAdd("SquidShutdown", &StopEventLoop, this, (double) (wait + 1), 1, false);
+    eventAdd("SquidShutdown", &FinalShutdownRunners, this, (double) (wait + 1), 1, false);
 }
 
 static void
 usage(void)
 {
     fprintf(stderr,
             "Usage: %s [-cdhvzCFNRVYX] [-n name] [-s | -l facility] [-f config-file] [-[au] port] [-k signal]"
 #if USE_WIN32_SERVICE
             "[-ir] [-O CommandLine]"
 #endif
             "\n"
             "       -a port   Specify HTTP port number (default: %d).\n"
             "       -d level  Write debugging to stderr also.\n"
             "       -f file   Use given config-file instead of\n"
             "                 %s\n"
             "       -h        Print help message.\n"
 #if USE_WIN32_SERVICE
             "       -i        Installs as a Windows Service (see -n option).\n"
 #endif
             "       -k reconfigure|rotate|shutdown|"

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