[BUG]JSONException: level too large : 2048

[zhangzhen91]

问题描述

您好，长链表结构序列化字符串报以下错误

Exception in thread "main" com.alibaba.fastjson2.JSONException: level too large : 2048
	at com.alibaba.fastjson2.JSONWriterUTF16.startObject(JSONWriterUTF16.java:87)
	at com.alibaba.fastjson2.writer.OWG_1_4_FlameTreeNode.write(Unknown Source)
	at com.alibaba.fastjson2.writer.FieldWriterList.writeList(FieldWriterList.java:253)
	at com.alibaba.fastjson2.writer.OWG_1_4_FlameTreeNode.write(Unknown Source)
	at com.alibaba.fastjson2.writer.FieldWriterList.writeList(FieldWriterList.java:253)
	at com.alibaba.fastjson2.writer.OWG_1_4_FlameTreeNode.write(Unknown Source)
	at com.alibaba.fastjson2.writer.FieldWriterList.writeList(FieldWriterList.java:253)
	at com.alibaba.fastjson2.writer.OWG_1_4_FlameTreeNode.write(Unknown Source)
	at com.alibaba.fastjson2.writer.FieldWriterList.writeList(FieldWriterList.java:253)
	at com.alibaba.fastjson2.writer.OWG_1_4_FlameTreeNode.write(Unknown Source)
	at com.alibaba.fastjson2.writer.FieldWriterList.writeList(FieldWriterList.java:253)

环境信息

请填写以下信息：

• OS信息： mac
• JDK信息： Openjdk 1.8.0_312
• 版本信息：fastjson 2.0.57

重现步骤

如何操作可以重现该问题：

1. 执行以下方法可复现

public class FlameTreeNode {
    private String n;
    private long s;
    private long v;
    private List<FlameTreeNode> c;

    public FlameTreeNode(String name, long self, long total) {
        this.n = name;
        this.s = self;
        this.v = total;
        this.c = new ArrayList();
    }

    public FlameTreeNode() {
    }

    public void addChild(FlameTreeNode child) {
        this.c.add(child);
    }

    public String getN() {
        return this.n;
    }

    public void setN(String n) {
        this.n = n;
    }

    public long getS() {
        return this.s;
    }

    public void setS(long s) {
        this.s = s;
    }

    public long getV() {
        return this.v;
    }

    public void setV(long v) {
        this.v = v;
    }

    public List<FlameTreeNode> getC() {
        return this.c;
    }

    public void setC(List<FlameTreeNode> c) {
        this.c = c;
    }

    public int countNodes() {
        int count = 1;

        for(FlameTreeNode child : this.c) {
            count += child.countNodes();
        }

        return count;
    }
   
   public static void main(String[] args) throws Exception {
        FlameTreeNode root = new FlameTreeNode("test", 1, 1);
        FlameTreeNode parent = root;
        for (int i = 0; i < 2050; i++) {
            FlameTreeNode item = new FlameTreeNode("test", 1, 1);
            parent.addChild(item);
            parent = item;
        }
        System.out.println(root.countNodes());
        System.out.println(JSON.toJSONString(root));
    }
}

期待的正确结果

如果存在2048限制，是否可以通过方法配置maxLevel? 实际场景中存在不少超过此阈值的. 另我尝试用反射修改maxLevel，发现maxLevel貌似大于实际链表长度也不行，必须要大很多才行，麻烦帮忙看一下

相关日志输出

请复制并粘贴任何相关的日志输出。

附加信息

此链表无循环

[mengnankkkk]

我觉得可以通过设置maxlevel来增加这个阈值，但是如果设置太多的话会出现oom。我写了一个方法，求CR. #3658