Bug 38806

I use mod_jk 1.2.15 in a failover configuration with session stickyness:

# List of available workers
worker.list=failover
 
# Master worker
# Take care that the jvmRoute attribute in the Engine tag is set to master
# for the Tomcat addressed by MASTER_HOST and MASTER_PORT
worker.master.port=MASTER_PORT
worker.master.host=MASTER_HOST
worker.master.type=ajp13
worker.master.cachesize=10
worker.master.cache_timeout=600
worker.master.socket_keepalive=1
worker.master.prepost_timeout=300
worker.master.reply_timeout=120000
worker.master.recovery_options=3
# redirect to backup if master fails
worker.master.redirect=backup

# Backup worker for failover
# Take care that the jvmRoute attribute in the Engine tag is set to backup
# for the Tomcat addressed by BACKUP_HOST and BACKUP_PORT
worker.backup.port=BACKUP_PORT
worker.backup.host=BACKUP_HOST
worker.backup.type=ajp13
worker.backup.cachesize=10
worker.backup.cache_timeout=600
worker.backup.socket_keepalive=1
worker.backup.prepost_timeout=300
worker.backup.reply_timeout=120000
worker.backup.recovery_options=3
# Set worker to disabled. This means it gets only requests in the case that
# - The session route points to this worker
# - In the failover case (see redirect setting for master above)
worker.backup.disabled=1

# Failover worker
worker.failover.type=lb
worker.failover.balanced_workers=master, backup

Once I got a session from the backup worker the session stays on this disabled
worker which is correct and expected. But if the backup server goes into error
state it does not recover from this state as disabled workers are not retried.
This is bad in the case that the disabled worker had been choosen because of
session stickyness. The attached patch fixes this.