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https://issues.apache.org/jira/browse/DERBY-7123?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Richard N. Hillegas updated DERBY-7123:
---------------------------------------
Bug behavior facts: Crash,Seen in production
Component/s: (was: JDBC)
Network Server
Issue & fix info: Repro attached
Urgency: Normal
> Opening many client connections at the same time can hang
> ---------------------------------------------------------
>
> Key: DERBY-7123
> URL: https://issues.apache.org/jira/browse/DERBY-7123
> Project: Derby
> Issue Type: Bug
> Components: Network Server
> Affects Versions: 10.14.2.0, 10.15.2.0
> Environment: Test run on
> $ uname -a
> Linux mattiasl-laptop2020 5.8.0-63-generic #71-Ubuntu SMP Tue Jul 13 15:59:12
> UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
> Reporter: Mattias Lundstrom
> Priority: Major
> Attachments: DerbyTest.java
>
>
> If many connections are opened at the same time towards a Derby network
> server using ClientConnectionPoolDataSource.getPooledConnection, then this
> operation may hang indefinitely.
> This has been tested with network server version 10.14.2.0 and 10.15.2.0 and
> the same client versions.
> Attached test client program (for 10.15.2.0) to show the behavior. It just
> repeatedly tries to open 1000 connections in parallel to the same server (in
> the production system, there were much fewer connections, but that makes it
> is harder to reproduce). It is generally slow and sometimes seems to hang
> indefinitely.
> Test can be run by just having a local network server and create a database
> and then
> {code:java}
> $ javac -cp derbyclient.jar:derbytools.jar DerbyTest.java
> $ java -cp .:derbyclient.jar:derbytools.jar DerbyTest localhost 1527 seconddb
> {code}
> (where "seconddb" is the test database)
> Testing seems to show that if the getPooledConnection operation is
> synchronized, the problem disappears (see commented out code in test
> program). We are using this workaround in our application for now.
> Running the test program, sometimes the connection seems to hang indefinitely
> or at the very least be extremely slow. In these situations neither client
> nor server consumes any CPU and the client seems to wait for IO from the
> server.
> Stacktrace from client
> {quote}[email protected]/java.net.SocketInputStream.socketRead0(Native
> Method)
>
> [email protected]/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
>
>
> [email protected]/java.net.SocketInputStream.read(SocketInputStream.java:168)
>
> [email protected]/java.net.SocketInputStream.read(SocketInputStream.java:140)
> app//org.apache.derby.client.net.Reply.fill(Reply.java:172)
>
> app//org.apache.derby.client.net.Reply.ensureALayerDataInBuffer(Reply.java:216)
>
> app//org.apache.derby.client.net.Reply.readDssHeader(Reply.java:319)
>
> app//org.apache.derby.client.net.Reply.startSameIdChainParse(Reply.java:1085)
>
> app//org.apache.derby.client.net.NetConnectionReply.readExchangeServerAttributes(NetConnectionReply.java:56)
>
>
> app//org.apache.derby.client.net.NetConnection.readServerAttributesAndKeyExchange(NetConnection.java:764)
>
>
> app//org.apache.derby.client.net.NetConnection.flowServerAttributesAndKeyExchange(NetConnection.java:708)
>
>
> app//org.apache.derby.client.net.NetConnection.flowUSRIDONLconnect(NetConnection.java:562)
>
>
> app//org.apache.derby.client.net.NetConnection.flowConnect(NetConnection.java:359)
>
>
> app//org.apache.derby.client.net.NetConnection.initialize(NetConnection.java:274)
>
>
> app//org.apache.derby.client.net.NetConnection.<init>(NetConnection.java:260)
>
> app//org.apache.derby.client.net.ClientJDBCObjectFactoryImpl.newNetConnection(ClientJDBCObjectFactoryImpl.java:327)
>
>
> app//org.apache.derby.client.ClientPooledConnection.<init>(ClientPooledConnection.java:130)
>
>
> app//org.apache.derby.client.net.ClientJDBCObjectFactoryImpl.newClientPooledConnection(ClientJDBCObjectFactoryImpl.java:85)
>
>
> app//org.apache.derby.client.BasicClientDataSource.getPooledConnectionX(BasicClientDataSource.java:1619)
>
>
> app//org.apache.derby.client.BasicClientDataSource.getPooledConnectionMinion(BasicClientDataSource.java:1560)
>
>
> app//org.apache.derby.jdbc.ClientConnectionPoolDataSource.getPooledConnection(ClientConnectionPoolDataSource.java:69)
> {quote}
>
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