public synchronized IMemoryBlock exactAllocate(String name, MemoryBlockType memoryBlockType) {
    return exactAllocate(
        name, totalMemorySizeInBytes - allocatedMemorySizeInBytes, memoryBlockType);
  }
Try to allocate memory block with total memory size in bytes

@param name the name of memory block
@param memoryBlockType the type of memory block
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/memory/MemoryManager.java