Flags DB_CREATE | DB_RECOVER | DB_REGISTER generate a PANIC on a replica

Question

Hi,
I have a configuration with one master and one replica (coded in C++ and using an XML Container). If I use a PHP script to read the xml data on the replica, I notice that when the replica stops it prints with the following errors if I use flags DB_CREATE | DB_RECOVER | DB_REGISTER | DB_INIT_LOCK | DB_INIT_LOG |DB_INIT_MPOOL | DB_INIT_TXN | DB_INIT_REP | DB_THREAD :
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: PANIC: fatal region error detected; run recovery
client/: ignoring event 1
client/: File handles still open at environment close
client/: Open file handle: client/__db.rep.db
client/: Open file handle: client/DbXmlHATest.dbxml
I don't get these errors if I remove flags DB_CREATE and DB_RECOVER.
Any explication for this behaviour ?

Answer 1

What version of BDB are you using for this configuration?dbxml 2.5.16, db 4.8.26
When you say "when the replica stops", do you mean that it gets the panic on its own or that you were trying to stop it (e.g. close the environment) when you got the panic?the process gets the panic when it tries to delete the XMLManager object which has adopted the dbenv object.
Did you specify a DB_REGISTER flag when opening the environment in your PHP script? I am not sure that DB_REGISTER is supported with PHP. I am checking on this internally. The reason this might be a problem is that one of the rules when using DB_REGISTER is that all applications using the environment must specify DB_REGISTER when opening the environment. I will let you know when I have an answer on PHP support for DB_REGISTER.with DB_REGISTER there is no issue. the panic is raised only when I use DB_CREATE | DB_RECOVER | DB_REGISTER | ... flags
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If it is not too much trouble, can you try your configuration with DB_CREATE but without DB_REGISTER? We don't think DB_CREATE is likely to be causing a problem and this would help us confirm that it is a DB_REGISTER issue.I tried every combinations of DB_CREATE, DB_RECOVER and DB_REGISTER, and the issue is raised by DB_RECOVER. It seems that DB_REGISTER is ignored and that recovery has been started by the PHP script. I get the same behaviour if I launch db_recover on the environnement of the replica when replication is running.