SpringBoot项目启动卡死问题调查

一、背景

今天，项目代码在合并了一个分支之后，启动卡死，无法正常启动

二、调查

首先，我们在IDEA中切换到那个有问题的分支，将日志改成DEBUG模式，启动，发现日志卡在了创建单例对象bohTokenUtil这里，而bohTokenUtil确实是新加入的代码

2023-03-08 18:43:20,766 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Creating shared instance of singleton bean 'mybatis-org.mybatis.spring.boot.autoconfigure.MybatisProperties'
2023-03-08 18:43:20,832 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Autowiring by type from bean name 'org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration' via constructor to bean named 'mybatis-org.mybatis.spring.boot.autoconfigure.MybatisProperties'
2023-03-08 18:43:20,832 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Autowiring by type from bean name 'org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration' via constructor to bean named 'org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@38c2c309'
2023-03-08 18:43:20,846 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Autowiring by type from bean name 'sqlSessionFactory' via factory method to bean named 'dataSource'
2023-03-08 18:43:20,856 DEBUG [ ] [main] o.m.spring.SqlSessionFactoryBean: Property 'mapperLocations' was not specified.
2023-03-08 18:43:20,860 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Creating shared instance of singleton bean 'sqlSessionTemplate'
2023-03-08 18:43:20,860 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Autowiring by type from bean name 'sqlSessionTemplate' via factory method to bean named 'sqlSessionFactory'
2023-03-08 18:43:20,929 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Creating shared instance of singleton bean 'interfaceRunningService'
2023-03-08 18:43:20,946 DEBUG [ ] [main] o.s.b.f.s.DefaultListableBeanFactory: Creating shared instance of singleton bean 'bohTokenUtil'

同时也看了下启动之后的线程情况，发现线程卡死在了ConcurrentHashMap的computeIfAbsent方法

"main" #1 prio=5 os_prio=0 tid=0x0000000002d35800 nid=0x9cec runnable [0x0000000002c29000]
java.lang.Thread.State: RUNNABLE
at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1718)
at org.springframework.cache.concurrent.ConcurrentMapCache.get(ConcurrentMapCache.java:144)
at com.ulisesbocchio.jasyptspringboot.caching.CachingDelegateEncryptablePropertySource.getProperty(CachingDelegateEncryptablePropertySource.java:34)
at com.ulisesbocchio.jasyptspringboot.wrapper.EncryptableMapPropertySourceWrapper.getProperty(EncryptableMapPropertySourceWrapper.java:31)
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:85)
at org.springframework.core.env.PropertySourcesPropertyResolver.getPropertyAsRawString(PropertySourcesPropertyResolver.java:74)
at org.springframework.core.env.AbstractPropertyResolver$$Lambda$22/1727361096.resolvePlaceholder(Unknown Source)
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:151)
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124)
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:237)
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:211)
at org.springframework.core.env.AbstractEnvironment.resolveRequiredPlaceholders(AbstractEnvironment.java:575)
at com.ulisesbocchio.jasyptspringboot.resolver.DefaultPropertyResolver$$Lambda$239/2091586824.apply(Unknown Source)
at java.util.Optional.map(Optional.java:215)
at com.ulisesbocchio.jasyptspringboot.resolver.DefaultPropertyResolver.resolvePropertyValue(DefaultPropertyResolver.java:38)
at com.ulisesbocchio.jasyptspringboot.resolver.DefaultLazyPropertyResolver.resolvePropertyValue(DefaultLazyPropertyResolver.java:42)
at com.ulisesbocchio.jasyptspringboot.EncryptablePropertySource.getProperty(EncryptablePropertySource.java:20)
at com.ulisesbocchio.jasyptspringboot.caching.CachingDelegateEncryptablePropertySource.lambda$getProperty$0(CachingDelegateEncryptablePropertySource.java:34)
at com.ulisesbocchio.jasyptspringboot.caching.CachingDelegateEncryptablePropertySource$$Lambda$216/194408994.call(Unknown Source)
at org.springframework.cache.concurrent.ConcurrentMapCache.lambda$get$0(ConcurrentMapCache.java:146)
at org.springframework.cache.concurrent.ConcurrentMapCache$$Lambda$217/990830650.apply(Unknown Source)
at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
locked <0x000000077d130ce8> (a java.util.concurrent.ConcurrentHashMap$ReservationNode)
at org.springframework.cache.concurrent.ConcurrentMapCache.get(ConcurrentMapCache.java:144)
at com.ulisesbocchio.jasyptspringboot.caching.CachingDelegateEncryptablePropertySource.getProperty(CachingDelegateEncryptablePropertySource.java:34)
at com.ulisesbocchio.jasyptspringboot.wrapper.EncryptableMapPropertySourceWrapper.getProperty(EncryptableMapPropertySourceWrapper.java:31)
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:85)
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:62)
at org.springframework.core.env.AbstractEnvironment.getProperty(AbstractEnvironment.java:539)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:137)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:133)
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:85)
at org.springframework.core.env.PropertySourcesPropertyResolver.getPropertyAsRawString(PropertySourcesPropertyResolver.java:74)
at org.springframework.core.env.AbstractPropertyResolver$$Lambda$22/1727361096.resolvePlaceholder(Unknown Source)
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:145)
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124)
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:237)
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:211)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.lambda$processProperties$0(PropertySourcesPlaceholderConfigurer.java:175)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$$Lambda$187/632841653.resolveStringValue(Unknown Source)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:851)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1185)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1164)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1378)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:575)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$153/605705199.getObject(Unknown Source)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
locked <0x00000006c4927600> (a java.util.concurrent.ConcurrentHashMap)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1244)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1164)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1378)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:575)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$153/605705199.getObject(Unknown Source)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
locked <0x00000006c4927600> (a java.util.concurrent.ConcurrentHashMap)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:525)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:630)
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1378)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:575)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$153/605705199.getObject(Unknown Source)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
locked <0x00000006c4927600> (a java.util.concurrent.ConcurrentHashMap)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:525)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:630)
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1378)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:575)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$153/605705199.getObject(Unknown Source)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
locked <0x00000006c4927600> (a java.util.concurrent.ConcurrentHashMap)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:846)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
locked <0x00000006c3fec3a0> (a java.lang.Object)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
at com.rydeen.boh.InterfaceApplication.main(InterfaceApplication.java:18)

沿着栈信息往下看，发现是在populateBean之后出现的异常，怀疑是属性填充导致的问题

于是看类bohTokenUtil的属性，终于发现了问题

这里使用了@Value来引入配置文件里的配置

判断前后名称写的一致，导致了死循环，于是将bohTokenCacheExpireInSeconds改成了BOH_TOKEN_CACHE_EXPIRE_IN_SECONDS再次启动，终于可以正常启动了

三、事后分析

后来我就好奇，为什么就会卡死了呢，为什么不报错，看栈信息，最后应该是卡死在了ConcurrentHashMap的computeIfAbsent方法上，于是就去跟了下源码，找到了调用computeIfAbsent方法的地方，是ConcurrentMapCache的get方法

这个this.store就是一个ConcurrentHashMap，可以看到computeIfAbsent的第二个参数是一个Lambda表达式，在里面又调用了get方法里传过来的valuLoader.call()方法，又往上去找调用的地方，是CachingDelegateEncryptablePropertySource的getProperty方法

发现valuLoader也是个Lambda表达式，调用的是getProperty方法，这个方法最终还是会调用到CachingDelegateEncryptablePropertySource的getProperty方法，我们通过之前的栈信息也可以看到调用了两次

所以相当于并发操作了ConcurrentHashMap的computeIfAbsent方法，放入了同一个key，所以怀疑是不是这种情况会有问题，于是又跟了下computeIfAbsent的源码

public V computeIfAbsent(K key, Function mappingFunction) {
    if (key == null || mappingFunction == null)
        throw new NullPointerException();
    //两个相同的key一定是相同的hashCode,所以h也是一样的
    int h = spread(key.hashCode());
    V val = null;
    int binCount = 0;
    for (Node[] tab = table;;) {
        Node f; int n, i, fh;
        if (tab == null || (n = tab.length) == 0)
            tab = initTable();
        else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
            //1、key1会走进这里,创建一个占位的Node,这样会导致key2这里不会进来
            Node r = new ReservationNode();
            synchronized (r) {
                if (casTabAt(tab, i, null, r)) {
                    binCount = 1;
                    Node node = null;
                    try {
                        //2、调用Lambda表达式,进行计算等待返回值
                        if ((val = mappingFunction.apply(key)) != null)
                            node = new Node(h, key, val, null);
                    } finally {
                        //将计算结果创建Node,顶替掉占位的Node
                        setTabAt(tab, i, node);
                    }
                }
            }
            if (binCount != 0)
                break;
        }
        else if ((fh = f.hash) == MOVED)
            tab = helpTransfer(tab, f);
        else {
            //由于key1占住了位置,所以key2会走到这里
            boolean added = false;
            synchronized (f) {
                if (tabAt(tab, i) == f) {
                    if (fh >= 0) {
                        //key2不满足这个条件
                        binCount = 1;
                        for (Node e = f;; ++binCount) {
                            K ek; V ev;
                            if (e.hash == h &&
                                ((ek = e.key) == key ||
                                 (ek != null && key.equals(ek)))) {
                                val = e.val;
                                break;
                            }
                            Node pred = e;
                            if ((e = e.next) == null) {
                                //key2会走这里
                                if ((val = mappingFunction.apply(key)) != null) {
                                    added = true;
                                    pred.next = new Node(h, key, val, null);
                                }
                                break;
                            }
                        }
                    }
                    else if (f instanceof TreeBin) {
                        //key2也不满足这个条件
                        binCount = 2;
                        TreeBin t = (TreeBin)f;
                        TreeNode r, p;
                        if ((r = t.root) != null &&
                            (p = r.findTreeNode(h, key, null)) != null)
                            val = p.val;
                        else if ((val = mappingFunction.apply(key)) != null) {
                            added = true;
                            t.putTreeVal(h, key, val);
                        }
                    }
                }
            }
            if (binCount != 0) {
                if (binCount >= TREEIFY_THRESHOLD)
                    treeifyBin(tab, i);
                if (!added)
                    return val;
                break;
            }
        }
    }
    if (val != null)
        addCount(1L, binCount);
    return val;
}

发现key1会走第12行和第21行，在21行会调用Lambda表达式等待结果，这时候key2会进来，发现key1已经占住了位置，会走36行的else里，而key2不满足39行和61行的if条件，循环中没有可以跳出的地方，就陷入了死循环。后来上网了解，这是jdk1.8的一个bug，在1.9中得到了解决，在后面补充了一个else if，如果是ReservationNode类型就抛IllegalStateException异常，

else if (f instanceof ReservationNode)
    throw new IllegalStateException("Recursive update");