让人讨厌的多线程代码，性能怎么优化！

Benchmark                                 Mode  Cnt     Score      Error   Units
SynchronizedNormalBenchmark.sync         thrpt   10  2554.628 ± 5098.059  ops/ms
SynchronizedNormalBenchmark.threadLocal  thrpt   10  3750.902 ±  103.528  ops/ms
========去掉业务影响========  
Benchmark                                 Mode  Cnt        Score        Error   Units
SynchronizedNormalBenchmark.sync         thrpt   10    26905.514 ±   1688.600  ops/ms
SynchronizedNormalBenchmark.threadLocal  thrpt   10  7041876.244 ± 355598.686  ops/ms

synchronized void syncMethod(){
  System.out.println("syncMethod");
}
======字节码=====
synchronized void syncMethod();
    descriptor: ()V
    flags: ACC_SYNCHRONIZED
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #4                 
         3: ldc           #5                         
         5: invokevirtual #6           
         8: return

void syncBlock(){
    synchronized (Test.class){
    }
}
======字节码======
void syncBlock();
    descriptor: ()V
    flags:
    Code:
      stack=2, locals=3, args_size=1
         0: ldc           #2 
         2: dup
         3: astore_1
         4: monitorenter
         5: aload_1
         6: monitorexit
         7: goto          15
        10: astore_2
        11: aload_1
        12: monitorexit
        13: aload_2
        14: athrow
        15: return
      Exception table:
         from    to  target type
             5     7    10   any
            10    13    10   any

"http-nio-8084-exec-120" #143 daemon prio=5 os_prio=31 cpu=122.86ms elapsed=317.88s tid=0x00007fedd8381000 nid=0x1af03 waiting for monitor entry  [0x00007000150e1000]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at java.io.BufferedInputStream.read([email protected]/BufferedInputStream.java:263)
    - waiting to lock <0x0000000782e1b590> (a java.io.BufferedInputStream)
    at org.apache.commons.httpclient.HttpParser.readRawLine(HttpParser.java:78)
    at org.apache.commons.httpclient.HttpParser.readLine(HttpParser.java:106)
    at org.apache.commons.httpclient.HttpConnection.readLine(HttpConnection.java:1116)
    at org.apache.commons.httpclient.HttpMethodBase.readStatusLine(HttpMethodBase.java:1973)
    at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodBase.java:1735)

synchronized (lock){
    try {
         lock.wait();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

"wait-demo" #12 prio=5 os_prio=31 cpu=0.14ms elapsed=12.58s tid=0x00007fb66609e000 nid=0x6103 in Object.wait()  [0x000070000f2bd000]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait([email protected]/Native Method)
    - waiting on <0x0000000787b48300> (a java.lang.Object)
    at java.lang.Object.wait([email protected]/Object.java:326)
    at WaitDemo.lambda$main$0(WaitDemo.java:7)
    - locked <0x0000000787b48300> (a java.lang.Object)
    at WaitDemo$$Lambda$14/0x0000000800b44840.run(Unknown Source)
    at java.lang.Thread.run([email protected]/Thread.java:830)

public synchronized void a(){
    b();
}
public synchronized void b(){
    c();
}
public synchronized void c(){
}

ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
    Lock readLock = lock.readLock();
    Lock writeLock = lock.writeLock();

    public void put(K k, V v){
        writeLock.lock();
        try {
            map.put(k, v);
        } finally {
            writeLock.unlock();
        }
    }
...

public ReentrantReadWriteLock(boolean fair){
        sync = fair ? new FairSync() : new NonfairSync();
        readerLock = new ReadLock(this);
        writerLock = new WriteLock(this);
}

Benchmark                      Mode  Cnt      Score      Error   Units
FairVSNoFairBenchmark.fair    thrpt   10    186.144 ±   27.462  ops/ms
FairVSNoFairBenchmark.nofair  thrpt   10  35195.649 ± 6503.375  ops/ms

public class DeadLockDemo {
    public static void main(String[] args){
        Object object1 = new Object();
        Object object2 = new Object();
        Thread t1 = new Thread(() -> {
            synchronized (object1) {
                try {
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (object2) {
                }
            }
        }, "deadlock-demo-1");

        t1.start();
        Thread t2 = new Thread(() -> {
            synchronized (object2) {
                synchronized (object1) {
                }
            }
        }, "deadlock-demo-2");
        t2.start();
    }
}

public class LockLessDemo {
    List<String> list1 = new ArrayList<>();
    List<String> list2 = new ArrayList<>();
    public synchronized void addList1(String v){
        this.list1.add(v);
    }
    public synchronized void addList2(String v){
        this.list2.add(v);
    }
}

public class LockLessDemo {
    List<String> list1 = new ArrayList<>();
    List<String> list2 = new ArrayList<>();
    final Object lock1 = new Object();
    final Object lock2 = new Object();
    public void addList1(String v){
        synchronized (lock1) {
            this.list1.add(v);
        }
    }
    public void addList2(String v){
        synchronized (lock2) {
            this.list2.add(v);
        }
    }
}

public class LockTimeDemo {
    List<String> list = new ArrayList<>();
    final Object lock = new Object();
    public void addList(String v){
        synchronized (lock) {
            slowMethod();
            this.list.add(v);
        }
    }
    public void slowMethod(){
    }
}

String m1(){
    StringBuffer sb = new StringBuffer();
    sb.append("");
    return sb.toString();
}