Fix bug for multi path file loading. Opt code checking for multi-path commitlog path in storePathCommitLog.

change default value of org.apache.rocketmq.store.config.MessageStoreConfig#MULTI_PATH_SPLITTER to ',' and can be changed by System.getProperty("rocketmq.broker.multiPathSplitter")

add path empty check to avoid error log in org.apache.rocketmq.store.DefaultMessageStore#getRuntimeInfo

1. fix initial value of physicRatio in org.apache.rocketmq.broker.processor.SendMessageProcessor#diskUtil
2. use minPhysicsUsedRatio instead of max in org.apache.rocketmq.store.DefaultMessageStore#getRuntimeInfo

Signed-off-by: Nzhangyang21 <zhangyang21@xiaomi.com>

[ISSUE 3194] [PART A] Use LongAdder instead of AtomicLong in BrokerStatsService to improve performance. (#3195)

[ISSUE 2883] Improve performance of string2messageProperties/messageProperties2String, and save 1 byte for each message.

* Remove putMessage/putMessages method in CommitLog which has too many duplicated code.

* Optimise performance of asyncPutMessage (extract some code out of putMessage lock)

* extract generation of msgId out of lock in CommitLog (now only for single message processor)

* extract generation of topicQueueTable key out of sync code

* extract generation of msgId out of lock in CommitLog (for batch)

* fix ipv6 problem introduced in commit "Optimise performance of asyncPutMessage (extract some code out of putMessage lock)"

[ISSUE #3099] Fix the incorrect judegment  'writePos - lastCommittedPosition > commitLeastPages' in the method 'commit0' of class 'MappedFile' (#3125)

[Part C] Improve produce performance in M/S mode.

* Optimise lock in WaitNotifyObject

* Remove lock in HAService

* Remove lock in GroupCommitService

Signed-off-by: Nzhangyang21 <zhangyang21@xiaomi.com>

Signed-off-by: Nzhangyang <Git_Yang@163.com>

Signed-off-by: Nzhangyang <Git_Yang@163.com>

* Delete README

* docs(reblance design): modify typographical issues

There is still more room for optimization, so one task is reserved here.

* [ISSUE #2865] Batch message send bug fix (#2866)

* [DLedgerCommitLog] Batch message send bug fix
Signed-off-by: Nzhangyang <Git_Yang@163.com>

* [DLedgerCommitLog] Batch message send bug fix2
Signed-off-by: Nzhangyang <Git_Yang@163.com>

* Revert "[ISSUE #2865] Batch message send bug fix (#2866)" (#2912)

This reverts commit 16694485.

* Revert "Revert "[ISSUE #2865] Batch message send bug fix (#2866)" (#2912)"

This reverts commit 129d7e2b.
Co-authored-by: NGit_Yang <30995057+Git-Yang@users.noreply.github.com>

This reverts commit 16694485.

* [DLedgerCommitLog] Batch message send bug fix
Signed-off-by: Nzhangyang <Git_Yang@163.com>

* [DLedgerCommitLog] Batch message send bug fix2
Signed-off-by: Nzhangyang <Git_Yang@163.com>

Change default value of some parameters: sendMessageThreadPoolNums/useReentrantLockWhenPutMessage/flushCommitLogTimed/endTransactionThreadPoolNums