Random 500 errors when running Stash - Database connection timeouts

Troubleshooting Databases

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  • Random 500 errors when visiting Stash in a web browser
  • Stash web pages don't always render fully (missing data or sections)
  • When pulling from, pushing or cloning to Stash, it responds with the error code 500 intermittently

Example command-line errors
$ git pull origin master
fatal: unable to access '': The requested URL returned error: 500
$ git pull origin master From
 * branch            master     -> FETCH_HEAD
Already up-to-date.



Look at the atlassian-stash.log: 

The exceptions can happen anytime Stash uses the database.  They should always have a database-related cause and the cause may indicate that the database connection was closed.  See below for some examples.

Example Microsoft SQL Server exception
2013-10-08 13:21:37,909 ERROR [http-bio-7990-exec-256] 801x6305x1,0:0:0:0:0:0:0:1 "GET /mvc/error500 HTTP/1.1" c.a.s.i.web.ErrorPageController There was an unhandled exception loading [/scm/project/repo.git/info/refs]
org.springframework.transaction.TransactionSystemException: Could not roll back Hibernate transaction; nested exception is org.hibernate.TransactionException: rollback failed
Caused by: org.hibernate.TransactionException: rollback failed
Caused by: org.hibernate.TransactionException: unable to rollback against JDBC connection
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
Example MySQL exception
ERROR [http-bio-7990-exec-2442] 19x26849x1, "GET /mvc/error500 HTTP/1.1" c.a.s.i.web.ErrorPageController There was an unhandled exception loading [/scm/ffa/devflow.git/info/refs]
org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.TransactionException: JDBC begin transaction failed:
Caused by: org.hibernate.TransactionException: JDBC begin transaction failed: 
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 197,409 milliseconds ago.  The last packet sent successfully to the server was 1 milliseconds ago.
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.


Stash does a periodic "ping" (a throwaway operation on the database that doesn't update any data) to keep the server from closing the connection as being idle. However, if the database server has aggressive timeouts configured, Stash's default heartbeat ping may not be fast enough. That can result in connections in the pool being closed. That, in turn, causes random operations to fail when the connection they get from the pool (all of which are expected to be open) is already closed.



You can either have Stash ping the database more frequently or increase the connection timeout.

Option 1) Tweak heartbeat rate on Stash

This solution will work for all databases.  Increase the heartbeat rate by add the following parameter to stash-config.properties:


That will cause Stash to heartbeat its database connections every minute instead of every 10 minutes (the default), avoiding connections in the pool from being closed by the remote server.

Option 2) Tweak database connection timeout parameter

This solution requires a different solution for each database:

Click here to expand for MySQL

The following command on a MySQL instance will reveal timeout parameters:

mysql> SHOW GLOBAL VARIABLES LIKE '%timeout%';
| Variable_name | Value |
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| innodb_lock_wait_timeout | 60 |
| innodb_rollback_on_timeout | OFF |
| interactive_timeout | 28800 |
| net_read_timeout | 30 |
| net_write_timeout | 30 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 180 |

On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). 

If your MySQL server is using wait_timeout = 180 (seconds) - 3 minutes - as a timeout for our DB connection created from Stash and Stash is configured with the default db.pool.idle.testInterval = 10 (minutes) set up as its keep alive the connection will be dropped out very often causing the exceptions above.

Last modified on Aug 14, 2015

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