jython测试记录

jython30个并发性能下降比较明显，有超时现象:

引用

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jstack看了一下大量被IdImpl.id()BLOCKED了

引用

"catalina-exec-111" daemon prio=10 tid=0x00002aaac0844000 nid=0x1a91 waiting for monitor entry [0x0000000052436000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.python.core.IdImpl.id(IdImpl.java:76)
        - waiting to lock <0x0000000704407ec8> (a org.python.core.IdImpl)
        at org.python.core.Py.id(Py.java:1830)
        at org.python.core.__builtin__.id(__builtin__.java:667)
        at org.python.core.BuiltinFunctions.__call__(__builtin__.java:82)
        at org.python.core.PyObject.__call__(PyObject.java:407)
        at copy$py._keep_alive$13(/data1/duitang/dist/sys/jython/Lib/copy.py:281)
        at copy$py.call_function(/data1/duitang/dist/sys/jython/Lib/copy.py)
        at org.python.core.PyTableCode.call(PyTableCode.java:165)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:149)
        at org.python.core.PyFunction.__call__(PyFunction.java:357)
        at copy$py.deepcopy$7(/data1/duitang/dist/sys/jython/Lib/copy.py:194)
        at copy$py.call_function(/data1/duitang/dist/sys/jython/Lib/copy.py)
        at org.python.core.PyTableCode.call(PyTableCode.java:165)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:301)
        at org.python.core.PyFunction.function___call__(PyFunction.java:406)
        at org.python.core.PyFunction.__call__(PyFunction.java:401)
        at django.db.models.sql.query$py.clone$18(/duitang/dist/sys/tomcat/webapps/ROOT/WEB-INF/lib-python/Lib/site-packages/django/db/models/sql/query.py:291)
        at django.db.models.sql.query$py.call_function(/duitang/dist/sys/tomcat/webapps/ROOT/WEB-INF/lib-python/Lib/site-packages/django/db/models/sql/query.py)
        at org.python.core.PyTableCode.call(PyTableCode.java:165)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:301)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:127)
        at org.python.core.PyFunction.__call__(PyFunction.java:347)
        at org.python.core.PyMethod.__call__(PyMethod.java:109)
        at django.db.models.query$py._clone$47(/duitang/dist/sys/tomcat/webapps/ROOT/WEB-INF/lib-python/Lib/site-packages/django/db/models/query.py:762)
        at django.db.models.query$py.call_function(/duitang/dist/sys/tomcat/webapps/ROOT/WEB-INF/lib-python/Lib/site-packages/django/db/models/query.py)
        at org.python.core.PyTableCode.call(PyTableCode.java:165)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:301)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:127)
        at org.python.core.PyFunction.__call__(PyFunction.java:347)

看了jython的实现大概明白了，他自己实现了一个WeakIdentityMap用来做cache，但不是线程安全，就粗暴的在 public synchronized long id(PyObject o)方法前面直接加上 synchronized。

package org.python.core;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.Map;

import org.python.util.Generic;

public class IdImpl {

    private WeakIdentityMap idMap = new WeakIdentityMap();

    private long sequentialId;

    public synchronized long id(PyObject o) {
        Object javaProxy = o.getJavaProxy();
        if (javaProxy != null) {
            return java_obj_id(javaProxy);
        } else {
            return java_obj_id(o);
        }
    }

    public String idstr(PyObject o) {
        return String.format("0x%x", id(o));
    }

    public synchronized long java_obj_id(Object o) {
        Long cand = (Long)idMap.get(o);
        if (cand == null) {
            long new_id = ++sequentialId;
            idMap.put(o, new_id);
            return new_id;
        }
        return cand.longValue();
    }
}

看了大概明白了，他自己实现了一个WeakIdentityMap用来做cache，但不是线程安全，就粗暴的在方法前面直接加上 synchronized。

这是他自己实现的WeakIdentityMap：

  public static class WeakIdentityMap {

        private transient ReferenceQueue<Object> idKeys = new ReferenceQueue<Object>();

        private Map<WeakIdKey, Object> objHashcodeToPyId = Generic.map();

        @SuppressWarnings("element-type-mismatch")
        private void cleanup() {
            Object k;
            while ((k = idKeys.poll()) != null) {
                objHashcodeToPyId.remove(k);
            }
        }

        private class WeakIdKey extends WeakReference<Object> {
            private final int hashcode;

            WeakIdKey(Object obj) {
                super(obj, idKeys);
                hashcode = System.identityHashCode(obj);
            }

            @Override
            public int hashCode() {
                return hashcode;
            }

            @Override
            public boolean equals(Object other) {
                Object obj = get();
                if (obj != null) {
                    return obj == ((WeakIdKey)other).get();
                } else {
                    return this == other;
                }
            }
        }

        // Used by test_jy_internals
        public int _internal_map_size() {
            return objHashcodeToPyId.size();
        }

        public void put(Object key, Object val) {
            cleanup();
            objHashcodeToPyId.put(new WeakIdKey(key), val);
        }

        public Object get(Object key) {
            cleanup();
            return objHashcodeToPyId.get(new WeakIdKey(key));
        }

        public void remove(Object key) {
            cleanup();
            objHashcodeToPyId.remove(new WeakIdKey(key));
        }

    }