How to ensure a point2pointConstraint can not be violated?

[silvesthu]

No matter how I adjust the parameters, including m_settings, cfm, erp,
Just can not make it stable.
Is there a way to achieve this?

I know all constraints are solved together,
but now I just want to use pickup in demoapplication,
but without break other point2pointconstraint.

I noticed there is a line of comment said
//very weak constraint for picking
But the truth is the p2pconstraint used in pickup is still too strong I think.