先了解下scan、hscan、sscan、zscan
http://doc.redisfans.com/key/scan.html
keys 為啥不安全？
- keys的操作會(huì)導(dǎo)致數(shù)據(jù)庫(kù)暫時(shí)被鎖住，其他的請(qǐng)求都會(huì)被堵塞；業(yè)務(wù)量大的時(shí)候會(huì)出問(wèn)題
Spring RedisTemplate實(shí)現(xiàn)scan
1. hscan sscan zscan
- 例子中的"field"是值redis的key，即從key為"field"中的hash中查找
- redisTemplate的opsForHash，opsForSet，opsForZSet 可以 分別對(duì)應(yīng) sscan、hscan、zscan
- 也可以使用
(JedisCommands) connection.getNativeConnection()的 hscan、sscan、zscan 方法實(shí)現(xiàn)cursor遍歷，參照下文2.2章節(jié)
try {
Cursor<Map.Entry<Object,Object>> cursor = redisTemplate.opsForHash().scan("field",
ScanOptions.scanOptions().match("*").count(1000).build());
while (cursor.hasNext()) {
Map.Entry<Object,Object> entry = cursor.next();
Object key = entry.getKey();
Object valueSet = entry.getValue();
}
//關(guān)閉cursor
cursor.close();
} catch (IOException e) {
e.printStackTrace();
}
- cursor.close(); 游標(biāo)一定要關(guān)閉，不然連接會(huì)一直增長(zhǎng)；可以使用
client listsinfo clientsinfo stats命令查看客戶端連接狀態(tài)，會(huì)發(fā)現(xiàn)scan操作一直存在 - 我們平時(shí)使用的redisTemplate.execute 是會(huì)主動(dòng)釋放連接的，可以查看源碼確認(rèn)
client list
......
id=1531156 addr=xxx:55845 fd=8 name= age=80 idle=11 flags=N db=0 sub=0 psub=0 multi=-1 qbuf=0 qbuf-free=0 obl=0 oll=0 omem=0 events=r cmd=scan
......
org.springframework.data.redis.core.RedisTemplate#execute(org.springframework.data.redis.core.RedisCallback<T>, boolean, boolean)
finally {
RedisConnectionUtils.releaseConnection(conn, factory);
}
- 代碼雖然只是調(diào)用一次scan方法，但是spring-data-redis已經(jīng)對(duì)scan做了封裝，這個(gè)scan結(jié)合cursor.hasNext會(huì)多次redis scan，最終拿到所有match的結(jié)果
2. scan
2.1 使用spring-data-redis封裝好的scan方法
public Set<String> scan(String matchKey) {
Set<String> keys = redisTemplate.execute((RedisCallback<Set<String>>) connection -> {
Set<String> keysTmp = new HashSet<>();
Cursor<byte[]> cursor = connection.scan(new ScanOptions.ScanOptionsBuilder().match("*" + matchKey + "*").count(1000).build());
while (cursor.hasNext()) {
keysTmp.add(new String(cursor.next()));
}
return keysTmp;
});
return keys;
}
2.2 使用redis.clients.jedis的MultiKeyCommands，自己循環(huán)scan
- 獲取
connection.getNativeConnection；connection.getNativeConnection()實(shí)際對(duì)象是Jedis（debug可以看出） ，Jedis實(shí)現(xiàn)了很多接口
public class Jedis extends BinaryJedis implements JedisCommands, MultiKeyCommands,
AdvancedJedisCommands, ScriptingCommands, BasicCommands, ClusterCommands, SentinelCommands
- 當(dāng) scan.getStringCursor() 存在 且不是 0 的時(shí)候，一直移動(dòng)游標(biāo)獲取
public Set<String> scan(String key) {
return redisTemplate.execute((RedisCallback<Set<String>>) connection -> {
Set<String> keys = Sets.newHashSet();
JedisCommands commands = (JedisCommands) connection.getNativeConnection();
MultiKeyCommands multiKeyCommands = (MultiKeyCommands) commands;
ScanParams scanParams = new ScanParams();
scanParams.match("*" + key + "*");
scanParams.count(1000); // 這個(gè)不是返回結(jié)果的數(shù)量，應(yīng)該是每次scan的數(shù)量
ScanResult<String> scan = multiKeyCommands.scan("0", scanParams);
while (null != scan.getStringCursor()) {
keys.addAll(scan.getResult()); // 這一次scan match到的結(jié)果
if (!StringUtils.equals("0", scan.getStringCursor())) { // 不斷拿著新的cursor scan，最終會(huì)拿到所有匹配的值
scan = multiKeyCommands.scan(scan.getStringCursor(), scanParams);
continue;
} else {
break;
}
}
return keys;
});
}
發(fā)散思考
cursor沒(méi)有close，到底誰(shuí)阻塞了，是 Redis 么
- 測(cè)試過(guò)程中，我基本只要發(fā)起十來(lái)個(gè)scan操作，沒(méi)有關(guān)閉cursor，接下來(lái)的請(qǐng)求都卡住了
redis側(cè)分析
-
client listsinfo clientsinfo stats查看
發(fā)現(xiàn) 連接數(shù) 只有 十幾個(gè)，也沒(méi)有阻塞和被拒絕的連接 -
config get maxclients查詢r(jià)edis允許的最大連接數(shù) 是 10000
1) "maxclients"
2) "10000"`
-
redis-cli在其他機(jī)器上也可以直接登錄 操作
綜上，redis本身沒(méi)有卡死
應(yīng)用側(cè)分析
-
netstat查看和redis的連接，6333是redis端口；連接一直存在
? ~ netstat -an | grep 6333
netstat -an | grep 6333
tcp4 0 0 xx.xx.xx.aa.52981 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52979 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52976 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52971 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52969 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52967 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52964 xx.xx.xx.bb.6333 ESTABLISHED
tcp4 0 0 xx.xx.xx.aa.52961 xx.xx.xx.bb.6333 ESTABLISHED
-
jstack查看應(yīng)用的堆棧信息
發(fā)現(xiàn)很多 WAITING 的 線程，全都是在獲取redis連接
所以基本可以斷定是應(yīng)用的redis線程池滿了
"http-nio-7007-exec-2" #139 daemon prio=5 os_prio=31 tid=0x00007fda36c1c000 nid=0xdd03 waiting on condition [0x00007000171ff000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006c26ef560> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at org.apache.commons.pool2.impl.LinkedBlockingDeque.takeFirst(LinkedBlockingDeque.java:590)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:441)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:362)
at redis.clients.util.Pool.getResource(Pool.java:49)
at redis.clients.jedis.JedisPool.getResource(JedisPool.java:226)
at redis.clients.jedis.JedisPool.getResource(JedisPool.java:16)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:276)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:469)
at org.springframework.data.redis.core.RedisConnectionUtils.doGetConnection(RedisConnectionUtils.java:132)
at org.springframework.data.redis.core.RedisTemplate.executeWithStickyConnection(RedisTemplate.java:371)
at org.springframework.data.redis.core.DefaultHashOperations.scan(DefaultHashOperations.java:244)
綜上，是應(yīng)用側(cè)卡死
后續(xù)
- 過(guò)了一個(gè)中午，redis
client lists顯示 scan 連接還在，沒(méi)有釋放；應(yīng)用線程也還是處于卡死狀態(tài) - 檢查
config get timeout，redis未設(shè)置超時(shí)時(shí)間，可以用config set timeout xxx設(shè)置，單位秒；但是設(shè)置了redis的超時(shí)，redis釋放了連接，應(yīng)用還是一樣卡住
1) "timeout"
2) "0"
-
netstat查看和redis的連接，6333是redis端口；連接從ESTABLISHED變成了CLOSE_WAIT； -
jstack和 原來(lái)表現(xiàn)一樣，卡在JedisConnectionFactory.getConnection
? ~ netstat -an | grep 6333
netstat -an | grep 6333
tcp4 0 0 xx.xx.xx.aa.52981 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52979 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52976 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52971 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52969 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52967 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52964 xx.xx.xx.bb.6333 CLOSE_WAIT
tcp4 0 0 xx.xx.xx.aa.52961 xx.xx.xx.bb.6333 CLOSE_WAIT
回顧一下TCP四次揮手
ESTABLISHED 表示連接已被建立
CLOSE_WAIT 表示遠(yuǎn)程計(jì)算器關(guān)閉連接，正在等待socket連接的關(guān)閉
和現(xiàn)象符合redis連接池配置
根據(jù)上面netstat -an基本可以確定 redis 連接池的大小是 8 ；結(jié)合代碼配置，沒(méi)有指定的話，默認(rèn)也確實(shí)是8
redis.clients.jedis.JedisPoolConfig
private int maxTotal = 8;
private int maxIdle = 8;
private int minIdle = 0;
- 如何配置更大的連接池呢？
A. 原配置
@Bean
public RedisConnectionFactory redisConnectionFactory() {
RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration();
redisStandaloneConfiguration.setHostName(redisHost);
redisStandaloneConfiguration.setPort(redisPort);
redisStandaloneConfiguration.setPassword(RedisPassword.of(redisPasswd));
JedisConnectionFactory cf = new JedisConnectionFactory(redisStandaloneConfiguration);
cf.afterPropertiesSet();
return cf;
}
readTimeout，connectTimeout不指定，有默認(rèn)值 2000 ms
org.springframework.data.redis.connection.jedis.JedisConnectionFactory.MutableJedisClientConfiguration
private Duration readTimeout = Duration.ofMillis(Protocol.DEFAULT_TIMEOUT);
private Duration connectTimeout = Duration.ofMillis(Protocol.DEFAULT_TIMEOUT);
B. 修改后配置
- 配置方式一：部分接口已經(jīng)Deprecated了
@Bean
public RedisConnectionFactory redisConnectionFactory() {
JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
jedisPoolConfig.setMaxTotal(16); // --最多可以建立16個(gè)連接了
jedisPoolConfig.setMaxWaitMillis(10000); // --10s獲取不到連接池的連接，
// --直接報(bào)錯(cuò)Could not get a resource from the pool
jedisPoolConfig.setMaxIdle(16);
jedisPoolConfig.setMinIdle(0);
JedisConnectionFactory cf = new JedisConnectionFactory(jedisPoolConfig);
cf.setHostName(redisHost); // -- @Deprecated
cf.setPort(redisPort); // -- @Deprecated
cf.setPassword(redisPasswd); // -- @Deprecated
cf.setTimeout(30000); // -- @Deprecated 貌似沒(méi)生效，30s超時(shí)，沒(méi)有關(guān)閉連接池的連接；
// --redis沒(méi)有設(shè)置超時(shí)，會(huì)一直ESTABLISHED；redis設(shè)置了超時(shí)，且超時(shí)之后，會(huì)一直CLOSE_WAIT
cf.afterPropertiesSet();
return cf;
}
- 配置方式二：這是群里好友給找的新的配置方式，效果一樣
RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration();
redisStandaloneConfiguration.setHostName(redisHost);
redisStandaloneConfiguration.setPort(redisPort);
redisStandaloneConfiguration.setPassword(RedisPassword.of(redisPasswd));
JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
jedisPoolConfig.setMaxTotal(16);
jedisPoolConfig.setMaxWaitMillis(10000);
jedisPoolConfig.setMaxIdle(16);
jedisPoolConfig.setMinIdle(0);
cf = new JedisConnectionFactory(redisStandaloneConfiguration, JedisClientConfiguration.builder()
.readTimeout(Duration.ofSeconds(30))
.connectTimeout(Duration.ofSeconds(30))
.usePooling().poolConfig(jedisPoolConfig).build());
Standalone Sentinel Cluster區(qū)別
待更新
