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Send queue is getting backed up
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November 27, 2017
11:30 am
Henk Helmantel
Forum Posts: 1502
Member Since:
May 28, 2013
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By default, the SMPP Gateways in Diafaan SMS Server are not set to the fastest throughput but to a throughput that can be handled by most SMPP servers. To increase the send speed you can change the following settings:

- Set the 'AsyncModeWindowSize' property to the largest value that the SMPP server supports
- Set the 'MaxMessagesPerMinute' or 'MaxMessagesPerSecond' to the largest value that the SMPP server supports
- Set the 'MaximumBatchSize' property to at least 5 times the maximum number of messages per second.

So if you set the 'MaxMessagesPerMinute' to 3000, the 'MaximumBatchSize' should be set to 500 or higher.

These properties only affect a single SMPP Gateway, if you set the 'MaxMessagesPerMinute' to 3000 it means that this gateway will not send more than 3000 message per minute through this gateway. If you have 10 SMPP Gateways with this settings the throughput will never be more than 30000 messages per minute. In practice, a throughput of 30000 messages per minute is not feasible with Diafaan SMS Server and the actual throughput will be a lot lower.

Regards, Henk

November 24, 2017
4:42 pm

Let me explain a little better...

We have a custom balancer we created that throttles out the messages at 5 message per minute per line

I believe what is happening is on some of our bigger clients that have 150+ lines to send, when the balancer sends the messages to Diafaan, it is causes the send queue backup issue during our busy time in the mornings.

We have 10 gateways all connected to the the same SMPP connection, and we have also created extra ports to help send.

The "Max Messages Per Min" was set to 3000 on each with a batch size of 500 on each of these gateways, does that mean max throughput should be 30,000 or is the 3000 collective through all the gateways since they are connected to the same SMPP carrier connection?

November 24, 2017
3:51 pm
Henk Helmantel
Forum Posts: 1502
Member Since:
May 28, 2013
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Hello Alan,

Has anything changed in your configuration or in the number of messages that you are sending? If the configuration and number of message has not changed recently then there might be a problem in the internal message queue database that Diafaan SMS Server uses. The easiest way to solve this is to close down the Diafaan SMS Server service and console program, remove the 'MessageExchange.*' and 'SendQueueProxy.*' files from the 'C:\ProgramData\Diafaan\Diafaan Message Server' folder and start the Diafaan SMS Server service and console program again. Do this when the send queue is empty, otherwise some of your messages will be lost.

There is also a possibility that the send queue slows down because of a virus scanner. It is a good idea to exclude the files in the 'C:\ProgramData\Diafaan\Diafaan Message Server' folder from your virus scanner, or at least the .sqlite files.

If you are sending more messages than usual then you might be exceeding the limits for the message throughput of the gateways that you have set up. If that is the case then the number of messages in the send queue will keep growing.

If you send the configuration of Diafaan SMS Server to email address '', I can have a look to see if there is anything in the configuration of the gateways that is slowing down the throughput. But usually the default settings are the optimal settings.

Regards, Henk

November 23, 2017
10:45 pm

We are noticing recently that our send queue is getting backed up when a lot of messages are being sent.

We are using a SMPP connection with 10 gateways to send so not sure why this is happening, but we will see up to 30K messages waiting in send queue before they get sent to carrier, and the only way it goes down is when traffic starts to slow down.

Is there a setting in the gateways that will allow more messages through?

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