Fix buffer size counting bug

[black-adder]

This bug was fixed in node client both the golang and java clients exhibit the same bug. The python client does its own random thing but we should make sure it's bug free.

• golang
• java
• python

[yurishkuro]

I don't think all clients have the same bug. It manifested in Node because the buffer size counter was used in the flush method. But we should double check.

[jkowall]

Clients are deprecated now, so this will not be fixed.