zookeeper node value最大值

zookeeper node value最大值为1M，不建议修改，

具体可以参考：https://zookeeper.apache.org/doc/r3.1.2/zookeeperAdmin.html的如下内容

jute.maxbuffer:
(Java system property: jute.maxbuffer)

This option can only be set as a Java system property. There is no zookeeper prefix on it. It specifies the maximum size of the data that can be stored in a znode. The default is 0xfffff, or just under 1M. If this option is changed, the system property must be set on all servers and clients otherwise problems will arise. This is really a sanity check. ZooKeeper is designed to store data on the order of kilobytes in size.

或者https://github.com/obulpathi/zookeeper 的如下内容：

Default ZNode size limit is 1MB. It can be increased by changing jute.maxbuffer Java system property for all of communicating ZooKeeper servers and clients. However, it is strongly discouraged to do that because it may cause performance drop and seriously disrupt operation of the whole system or even cause its malfunction. And another thing to remember - one megabyte limitation involves not only ZNode value, but also its key and a list of child node names. All the data is stored in the memory and duplicated on each server in ZooKeeper ensemble. This fact must be taken into account during the planning phase of the system development. Server machine should have enough RAM and correct JVM heap settings (max. 3/4 of the total amount of memory) to be able to operate properly for the most severe design conditions. Disk swapping would degrade ZooKeeper performance significantly. Each write operation is flushed to the disk. Thereby, operations that require extra low latencies or that perform intensive writes of large amount of data are wrong for ZooKeeper. Also, be aware that write speeds can not be increased by adding new instances to the ensemble; on the contrary, one can observe a slight performance drop on write operations.