* count lowish */
public static void reduceOpenFiles(IndexWriter w) {
// keep number of open files lowish
MergePolicy mp = w.getConfig().getMergePolicy();
if (mp instanceof LogMergePolicy) {
LogMergePolicy lmp = (LogMergePolicy) mp;
lmp.setMergeFactor(Math.min(5, lmp.getMergeFactor()));
} else if (mp instanceof TieredMergePolicy) {
TieredMergePolicy tmp = (TieredMergePolicy) mp;
tmp.setMaxMergeAtOnce(Math.min(5, tmp.getMaxMergeAtOnce()));
tmp.setSegmentsPerTier(Math.min(5, tmp.getSegmentsPerTier()));
}