How vb6 Handles Multiple Events ?

Posted on 2003-03-05
Medium Priority
Last Modified: 2012-06-27

I would like to have multiple(about 6-10)MSCOMM controls
created at design time as a control array.

so we have only one event handler.

The events are generated asynchronously according to the
data on the ports(not very often probably every 1-2
seconds ).

My question is how does vb handle multiple events that are
generated. Are some events lost if not handled very soon.
How many events can the windows OS & VB hold so that some
events are not lost?


Question by:prakrithk
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Assisted Solution

RanaHossain earned 150 total points
ID: 8078124
Hi Kodela,

I am writing a POP3 checker for my IIS server, which now uses upto 10 threads to check E-mail. Now with no e-mails, it takes about 1.3 seconds to check 8 e-mails..

So I guess what I am trying to say is, each thread has about 3 external events, which raises some more.. so if you are thinking one event every 1-2 seconds .. should be fine.

Accepted Solution

marconovaro earned 450 total points
ID: 8078337

Hi Kodela,

the events are managed in a synchronous way. That is, the full event code is executed, before "listening to" a new event. This means that you should not have problems. Furthermore, 1-2 seconds is not so much (you should execute the full code in some microseconds).

UNLESS you are going to use DoEvents in the MSComm_OnComm event: do not do this! This is because if you use DoEvents, you could receive again the same event, and enter a recursive loop, that could cause you bad errors (out of stack space).

If you fear not to cope with the speed of the upcoming events, do something like this:

- in the OnComm event, read the buffer and put it into a FIFO
- set a timer, and parse the FIFO buffer there.

This will "separate" the incoming events from the time you need to parse them

Hope this helps.

Expert Comment

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