Use edm::one modules to access PoolDBOutputService

[Dr15Jones]

The PoolDBOutputService appears to be properly thread safe by using a std::mutex. However, since the framework will still schedule multiple modules to run concurrently where those modules would then be fighting over the mutex lock and therefore some of them would stall. If, instead, the modules would be declared edm::one modules and would declare a SharedResource on the PoolDBOutputService, the framework would schedule only one module to talk to the service at a time and could run other modules concurrently which do not need the service.

Such a change is made easier because many of the modules that use the PoolDBOutputService appear to be templated classes: BoostIODBWriter<>, ConditionDBWriter<> and DummyCondDBWriter<>.

[cmsbuild]

A new Issue was created by @Dr15Jones Chris Jones.

@davidlange6, @Dr15Jones, @smuzaffar can you please review it and eventually sign/assign? Thanks.

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[Dr15Jones]

assign alca

[cmsbuild]

New categories assigned: alca

@mmusich,@cerminar,@arunhep,@franzoni,@ghellwig you have been requested to review this Pull request/Issue and eventually sign? Thanks

[tvami]

unassign alca
assign db

• I think this needs a DB signature, not AlCa

[tvami]

assign db

[cmsbuild]

New categories assigned: db

@ggovi you have been requested to review this Pull request/Issue and eventually sign? Thanks

[tvami]

With Giacomo leaving CMS, I looked into this issue. I understand of the current status is that most of the work was actually done by @mmusich in #40793 for ConditionDBWriter. I gave a try to resolve the problem in the remaining two files in the PR #41094

[tvami]

+db

[cmsbuild]

This issue is fully signed and ready to be closed.