Parallel processing of Workflow Deadline Monitoing in 4.6C

[Mike Gambier]

Hello fellow WUGgers,

We are faced with a bit of a new dilemma regarding WF Deadlines and seem to 
be faced with some difficult choices.

Our old dilemma was this: we used to run RSWWDHEX every 15 minutes to pick 
up our steps that had passed their deadline entries (SWWWIDH / SWWWIDEADL) 
until this started to time out during the SELECT statement pulled too many 
entries back (simply because we have so many Workflows running). We also had 
an issue with the standard program respawning itself whilst its predecessor 
job was still running which caused us a bit of grief. This last bit has been 
resolved since we hear in later SAP versions.

So, to fix these issues we cloned the program and built in a MAX HITS 
parameter to reduce the number of deadlines it processed per run and added a 
self-terminate subroutine to ensure no two jobs ran concurrently.

But, even after these changes we are faced with a NEW dilemma with WF 
Deadline Monitoring. Namely it has a nasty habit of loading up whatever 
server the job is run on to progress the deadline! This manifests itself in 
dailog process 'hogging' or excessive local tRFC entries in ARFCSSTATE where 
it can't get hold of a dialog process to use on that particular server 
(which can happen a lot if we have other heavy jobs running there). The load 
then shifts to RSARFCEX which then struggles with the load as everything is 
processed locally on whatever server it is run on.

Unlike the Event Queue there is no standard ready made Parallel processing 
option for Deadlines that we know of, at least not in 4.6C. So we're 
thinking of choosing one of these options:

1. Amend our Deadline Monitoring program (will require a mod to SAP code as 
well) to redirect the first RFC with a new custom destination that can be 
processed seperately to 'normal' Workflow tRFCs, e.g. 'WORKFLOW_DL_0100' 
instead of 'WORKFLOW_LOCAL_0100'. The new destination would be set up to 
point to a completely different server than the one the Deadline Monitor job 
is currently running on. This won't diminish the load on the server where 
dialog processes are available but at least it will shift the load on 
RSARFCEX when it runs. Obviously we would have to schedule a new run for 
RSARCFEX with this new destination into our schedule.

2. Same as 1 (mod required) but the new destination will point to a server 
group destination (rather than a single server) to spread the load across 
mutltiple servers when the tRFCs are converted into qRFCs. Has the added 
benefit of reusing the qRFC queue (and its standard config settings and 
transactions) to buffer the start of each new deadline being processed. Once 
a deadline step is executed, any tRFCs that result will be appended as 
WORKFLOW_LOCAL_0100 as normal because they will result from subsequent calls 
that will not affected by our mod setting. End result should be the START of 
each deadline process chain is distributed across multiple servers (and 
therefore will spread the demand for dialog processes accordingly), but any 
tRFCs that result will end up being chucked back into the 'local' pot. 
Unfortunately this would mean that our version of SWWDHEX would pass the 
baton on to RSQOWKEX (the outbound queue batch job) to actually progress the 
deadline, i.e do any real work. We would therefore have two batch jobs to 
watch and have a noticeable delay between deadlines being selected and 
deadlines actually being progressed. Whether we can live with this we just 
don't know. The issue of different deadlines for the same Workflow being 
progressed on different servers is also a concern but since we limit the 
number of deadlines we process per run anyway that is currently something we 
suffer from at the moment.

3. Dynamic destination determination (OSS Note 888279) applied to all 
Workflow steps, not just deadlines. Scary stuff. Breaks the concept of a 
single server 'owning' a deadline process chain in its entirety. Considering 
the volumes of Workflow we have, we're uncertain as to what impact this will 
have system-wide.

4. Redesign Deadline Monitoring to use the same persistence approach as 
Event Delivery and have a deadline queue. Complete overhaul using SWEQUEUE 
etc as a guide. Would be a lovely project to do but honestly we can't really 
justify the database costs, code changes and testing.

We are currently favouring option 2 as a realistic way forward as it seems 
to offer the simplest way of shifting the load around to prevent a single 
server from being hammered. It has risks and would require careful 
monitoring or the qRFC queues, but it seems a safer bet than overloading 
another single server (option 1), splitting up a single deadline chain 
across multiple servers (option 3) or costing the earth and becoming 
unsupportable (option 4).

Has anyone out there implemented option 3, the OSS Note? We'd love to 
know...

Or, if you have any alternative suggestions we'd be interested to hear them 
:)

Regards,

Mike GT

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