Provide configuration for minSize of JDBCPool in LoaderConnectionPool

When client uses gs-loader.sh in multiple processes, we observed high number of connections (over 200) to Postgres DB.
The connections didn't close after 10 minutes (xdb.jdbc.pool.idle)

In ObjectPool.java:
protected synchronized void packBuffer() {
while (buffer.size() > 0 && buffer.size() + out.size() > minSize) {
minSize by default is 1.
This means there would always be at least 1 PoolEntry in the pool which can explain why connection to Postgres isn't closed.

I think we can introduce a new configuration parameter to control minSize for JDBCPool. E.g.
Property.getInt("xdb.jdbc.pool.minsize", 0),

Pooling of loader connections is a new feature introduced in v. 2.0
We will see feedbacks and decide how to improve it.
Regarding your problem with high number of connections minSize probably would not affect.
First of all it depends on number of nodes: each node establishes at least one connection to each node database.
Next is concurrency: each concurrent query may require own set of loader connections.
You may want to limit maxSize, but you may see poor performance because of lack of available connections and see query timeouts.
Limiting number of GridSQL connections will effectively limit pool size.