fix all bugs

Author: Pengzna

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/memory/pool/impl/OperatorMemoryPool.java

@@ -125,7 +125,7 @@ public Object requireMemory(long bytes, MemoryPool requestingPool) {
             // use lock to ensure the atomicity of the two-step operation
             this.memoryActionLock.lock();
             // if free memory is enough, use free memory directly.
-            if (getFreeBytes() < bytes) {
+            if (getFreeBytes() >= bytes) {
                 LOG.debug("[{}] require {} bytes, there is enough free memory {} bytes, will " +
                          "require memory directly from self's free memory.",
                          this,