[PIG-3409] org.apache.pig.data.DefaultTuple hashcode perfomance issue

• Type: Bug
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 0.11
• Component/s: impl
• Assignee: Unassigned
• Reporter: Sergey
• Created: 02/Aug/13 10:46
• Updated: 09/Aug/13 08:18

Description

I've met serious perfomance issue.
please see visualvm screenshot.

Here is hashCode implementation from the class:

 @Override
    public int hashCode() {
        int hash = 17;
        for (Iterator<Object> it = mFields.iterator(); it.hasNext();) {
            Object o = it.next();
            if (o != null) {
                hash = 31 * hash + o.hashCode();
            }
        }
        return hash;
    }

I don't see any reason here to iterate over the whole tuple, aggregate hash value and then return it.

I can fix it, if it's possible to take part in dev process. I'm new to it

The idea for any join:
If we have a plan we know for sure which relations would be joined.
It means that we can precalculate hashcode values.
The difference is: m+n hashcode calculations or m*n (current implementation).
It think it should bring significant perfomance boost.