### Question:
MemoryManager { long getTotalMemoryPool() { return totalMemoryPool; } MemoryManager(Configuration conf); synchronized boolean isLowMemoryMode();  }### Answer:
@Test public void testConfig() throws Exception { Configuration conf = new Configuration(); conf.set("hive.exec.orc.memory.pool", "0.9"); MemoryManager mgr = new MemoryManager(conf); long mem = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage().getMax(); System.err.print("Memory = " + mem); long pool = mgr.getTotalMemoryPool(); assertTrue("Pool too small: " + pool, mem * 0.899 < pool); assertTrue("Pool too big: " + pool, pool < mem * 0.901); }