Android Question Remote Database Connector (RDC) stops to work

marcick · Aug 29, 2015

Hi all,
my app with RDC was working fine for several weeks, but suddenly I get the below error from server side. The RDC command is a simple "select" query and I have discovered that the error appears when the number of records of the result is more than a quota. I don't know this number but maybe around 2500 records.
Any idea ?

B4X:

        at java.lang.Thread.run(Thread.java:745)
2015-08-29 12:56:09.564:WARN::/
java.lang.IllegalStateException: STREAM
        at org.eclipse.jetty.server.Response.getWriter(Response.java:635)
        at anywheresoftware.b4a.remotedatabase.Servlet.doGet(Servlet.java:95)
        at anywheresoftware.b4a.remotedatabase.Servlet.doPost(Servlet.java:52)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:538
)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java
:478)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandl
er.java:937)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:
406)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandle
r.java:871)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.j
ava:117)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper
.java:110)
        at org.eclipse.jetty.server.Server.handle(Server.java:346)
        at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.
java:589)
        at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpCo
nnection.java:1065)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:823)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:220)

        at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:41
1)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEn
dPoint.java:535)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEnd
Point.java:40)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool
.java:529)
        at java.lang.Thread.run(Thread.java:745)

Erel · Aug 30, 2015

Is this the full error from the logs?

LucaMs · Aug 30, 2015

The exception ...

Caused by: java.lang.IllegalStateException: STREAM
at org.eclipse.jetty.server.Response.getWriter(Response.java:944)
...
... means that your code attempted to access HttpServletResponse.getWriter() after having already accessed HttpServletResponse.getOutputStream()

At the point in time when the .getWriter() call occurred, the state of the response was already in STREAM mode, hence the IllegalStateException

Thats not allowed per the servlet spec.

(source: http://stackoverflow.com/questions/...ream-when-writing-excel-file-as-response-with)

marcick · Aug 30, 2015

Erel: that is the full error on the rdc console, server side.
Lucams: if I change the parameters of the query so that to reduce the number of records of the result, it works (I can verify how many records are with a test on phpmyadmin). And I don't try a query if the previous one is still running.
Actually there are 4 users that make query to rdc every about 10 seconds. Maybe there are problems in rdc managing parallel query?

Erel · Aug 31, 2015

marcick said:
Maybe there are problems in rdc managing parallel query?

RDC can handle concurrent connections.

My guess is that the device closes the connection. Try to increase the request timeout.

marcick · Aug 31, 2015

Found where is the problem, let me put together the description

marcick · Aug 31, 2015

The command, server side is :

sql.cmd1 = SELECT * FROM `records` WHERE `Idx` > ?

where Idx is the primary key of the database

The actual result is about 10k records, but the size is not the real problem. I have discovered that one record of the result contain a field that should be a datetime but it is '0000-00-00 00:00:00'

And I obtain this error in the RDC console (the first row says everything)

B4X:

Command: query: RDC_CmdSync, took 0ms, client=5.90.142.55
java.sql.SQLException: Value '0000-00-00 00:00:00' can not be represented as jav
a.sql.Timestamp
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:998)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:937)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:872)
        at com.mysql.jdbc.ResultSetRow.getTimestampFast(ResultSetRow.java:921)
        at com.mysql.jdbc.ByteArrayRow.getTimestampFast(ByteArrayRow.java:130)
        at com.mysql.jdbc.ResultSetImpl.getTimestampInternal(ResultSetImpl.java:
5944)
        at com.mysql.jdbc.ResultSetImpl.getTimestamp(ResultSetImpl.java:5612)
        at com.mysql.jdbc.ResultSetImpl.getObject(ResultSetImpl.java:4587)
        at com.mchange.v2.c3p0.impl.NewProxyResultSet.getObject(NewProxyResultSe
t.java:2140)
        at anywheresoftware.b4a.remotedatabase.Servlet.executeQuery(Servlet.java
:160)
        at anywheresoftware.b4a.remotedatabase.Servlet.doGet(Servlet.java:78)
        at anywheresoftware.b4a.remotedatabase.Servlet.doPost(Servlet.java:52)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:538
)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java
:478)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandl
er.java:937)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:
406)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandle
r.java:871)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.j
ava:117)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper
.java:110)
        at org.eclipse.jetty.server.Server.handle(Server.java:346)
        at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.
java:589)
        at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpCo
nnection.java:1065)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:823)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:220)

        at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:41
1)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEn
dPoint.java:535)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEnd
Point.java:40)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool
.java:529)
        at java.lang.Thread.run(Thread.java:745)
2015-08-31 08:30:10.534:WARN::/
java.lang.IllegalStateException: STREAM
        at org.eclipse.jetty.server.Response.getWriter(Response.java:635)
        at anywheresoftware.b4a.remotedatabase.Servlet.doGet(Servlet.java:95)
        at anywheresoftware.b4a.remotedatabase.Servlet.doPost(Servlet.java:52)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:538
)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java
:478)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandl
er.java:937)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:
406)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandle
r.java:871)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.j
ava:117)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper
.java:110)
        at org.eclipse.jetty.server.Server.handle(Server.java:346)
        at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.
java:589)
        at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpCo
nnection.java:1065)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:823)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:220)

        at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:41
1)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEn
dPoint.java:535)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEnd
Point.java:40)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool
.java:529)
        at java.lang.Thread.run(Thread.java:745)

I will investigate why a record with a wronf datetime has been inserted in the database, but how avoid that RDC crashes in these cases ?
I'm not asking the query to do a filter based on datetime, just want to get the records as they are.
Any suggestion ?

Erel · Aug 31, 2015

Did it really crash? Can't you send more requests after this error?

The actual error happens in the MySQL driver.

marcick · Aug 31, 2015

Sorry I didn't use the correct word. No, it doesn't crash, everything continues to work.
So you mean we can do nothing?

Erel · Sep 1, 2015

The problem is between the stored data and the query. You need to fix it.

marcick · Sep 1, 2015

The same query in PhpMyAdmin doesn't generate any error and all the records are showed, included that one with the DateTime field '0000-00-00 00:00:00'
The problem appears only throught RDC, my app stops to work and can do anything. The app can't continue synchronization with the server because everytime the error is generated. I would like the app is able to manage and skip this error ....

Erel · Sep 1, 2015

The problem is in the JDBC driver. RDC cannot do anything about it. It is the JDBC driver that actually executes the query.

Can't you exclude the problematic items from the query results?

marcick · Sep 1, 2015

I have tried to modify the query in RDC like this

sql.cmd1 = SELECT * FROM `records` WHERE (`Idx` > ? AND 'Gtm' NOT LIKE "0000-00-00 00:00:00")

Funny workaround but ... it works !

Great Erel, thank you very much

DonManfred · Sep 1, 2015

marcick said:
(`Idx` > ? AND 'Gtm' NOT LIKE "0000-00-00 00:00:00"

have you tried to use

B4X:

(`Idx` > ? AND 'Gtm' <> "0000-00-00 00:00:00"

<> is much faster than a NOT LIKE

marcick · Sep 1, 2015

I'm really a beginner in MySql and just grabbed some samples here and there.
Moved to <> , works fine, thanks

Android Question Remote Database Connector (RDC) stops to work

marcick

Well-Known Member

Erel

B4X founder

LucaMs

Expert

marcick

Well-Known Member

Erel

B4X founder

marcick

Well-Known Member

marcick

Well-Known Member

Erel

B4X founder

marcick

Well-Known Member

Erel

B4X founder

marcick

Well-Known Member

Erel

B4X founder

marcick

Well-Known Member

DonManfred

Expert

marcick

Well-Known Member

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