Thanks Matt,
You wrote "With it off, producers will simply get errors when resources are exhausted". But in the description to producerFlowControl param on https://activemq.apache.org/per-destination-policies when the value is off it says "However, when the message store reaches capacity the producer will be throttled until resources are freed". Thanks, Daniel -----Original Message----- From: Matt Pavlovich <mattr...@gmail.com> Sent: Thursday, January 6, 2022 11:17 PM To: users@activemq.apache.org Subject: Re: Mismatch in documentation regarding producerFlowControl behavior CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. Turning off producer flow control just means the broker won’t pause fast producers to allow for consumers to catch up— it is a ’self-healing’ type feature. With it off, producers will simply get errors when resources are exhausted. The feature helps prevent producer-side errors in the scenario where a few micro pauses would allow things to settle down without any errors being thrown at all. -Matt Pavlovich > On Jan 6, 2022, at 12:36 PM, Daniel Navrotsky > <daniel.navrot...@driivz.com<mailto:daniel.navrot...@driivz.com>> wrote: > > Thank you Matt for the answer. > > I am trying to understand the difference between producerFlowControl=true or > false. I understand that the type of the cursor defines the resources. When > resources are exhausted the flow control will take place no matter if > producerFlowControl=true or false. Can you please bring an example of cursor > and message type where the behavior will be different depending on > producerFlowControl param? > > Thanks, > > Best regards, > Daniel > > -----Original Message----- > From: Matt Pavlovich <mattr...@gmail.com<mailto:mattr...@gmail.com>> > Sent: Thursday, January 6, 2022 7:42 PM > To: users@activemq.apache.org<mailto:users@activemq.apache.org> > Subject: Re: Mismatch in documentation regarding producerFlowControl behavior > > CAUTION: This email originated from outside of the organization. Do not click > links or open attachments unless you recognize the sender and know the > content is safe. > > > Daniel- > > The documentation looks correct. The “triggers” for producer flow control > vary based on the configurations and message type (persistent or > non-persistent). What is different in the various configuration noted below > are what what constitutes “resources” for non-persistent messages. > > For non-persistent messages: > > a. Default cursor will flow control when memoryLimit and/or tempUsageLimit > reached > -or- > b. vmQueueCurosr will flow control on memoryLimit only (since temp and store > usage are not used) > > Hope this helps. > > -Matt Pavlovich > >> On Jan 5, 2022, at 4:58 PM, Daniel Navrotsky >> <daniel.navrot...@driivz.com<mailto:daniel.navrot...@driivz.com>> wrote: >> >> Hello, >> >> It looks like there is a mismatch in the documentation. From piece 1 (below) >> I understand that messages would be shunted into the temporary file even if >> producerFlowControl=true, but from piece 2 it sounds like it only would >> happen if producerFlowControl=false >> >> >> Piece 1 >> https://activemq.apache.org/producer-flow-control.html >> Note that, since the introduction of the new file cursor in ActiveMQ 5.x, >> non-persisted messages are shunted into the temporary file store to reduce >> the amount of memory used for non-persistent messaging. As a result, you may >> find that a queue’s memoryLimit is never reached, as the cursor doesn’t use >> very much memory. If you really do want to keep all your non-persistent >> messages in memory, and stop producers when the limit is reached, you should >> configure the <vmQueueCursor> >> >> Piece 2 >> https://activemq.apache.org/per-destination-policies >> producerFlowControl - If true the broker will throttle (flow-control) the >> producer. Throttling is achieved either by withholding the producer’s ACK or >> by raising a javax.jms.ResourceAllocationException (that’s propagated back >> to the client) when local resources, e.g., memory and/or storage, have been >> exhausted. If false excess messages will be written to the message store to >> prevent memory exhaustion. However, when the message store reaches capacity >> the producer will be throttled until resources are freed. >> >> >> Best regards, >> Daniel >
