Redisson RMapCache无法读取缓存bug

之前排查过Redisson RMapCache无法读取缓存bug，在这里记录一下当时排查的思路和具体原因

测试代码

测试redisson版本为3.13.1，先看测试代码

@Slf4j
@SpringBootTest
public class RedissonTest {

    @Autowired
    private RedissonClient redissonClient;

    @Test
    public void test() {
        RMapCache<String, String> testRMapCache = redissonClient.getMapCache("testRMapCache");
        testRMapCache.fastPut("key", "value", 3, TimeUnit.SECONDS);
        try {
            //等缓存过期
            Thread.sleep(3100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 往缓存写入另外一个值
        testRMapCache.put("key", "anotherValue");
        String result = testRMapCache.get("key");
        // 尝试立刻读缓存，有可能获取到一个null，非必现
        System.out.println("result: " + result);
    }

}

本地测试还挺容易复现的，最后一步重新读取缓存的时候，直接读取到一个null

redis monitor 监听

这里先开启redis monitor 先看看具体执行了什么脚本（单次运行完需要清理redis中所有关联key，避免redisson定时任务的干扰）

127.0.0.1:6379> MONITOR
OK
// fastput执行的脚本
1746173814.962993 [0 192.168.188.1:39952] "EVAL" "local insertable = false; local value = redis.call('hget', KEYS[1], ARGV[5]); local t, val;if value == false then insertable = true; else t, val = struct.unpack('dLc0', value); local expireDate = 92233720368547758; local expireDateScore = redis.call('zscore', KEYS[2], ARGV[5]); if expireDateScore ~= false then expireDate = tonumber(expireDateScore) end; if t ~= 0 then local expireIdle = redis.call('zscore', KEYS[3], ARGV[5]); if expireIdle ~= false then expireDate = math.min(expireDate, tonumber(expireIdle)) end; end; if expireDate <= tonumber(ARGV[1]) then insertable = true; end; end; if tonumber(ARGV[2]) > 0 then redis.call('zadd', KEYS[2], ARGV[2], ARGV[5]); else redis.call('zrem', KEYS[2], ARGV[5]); end; if tonumber(ARGV[3]) > 0 then redis.call('zadd', KEYS[3], ARGV[3], ARGV[5]); else redis.call('zrem', KEYS[3], ARGV[5]); end; local maxSize = tonumber(redis.call('hget', KEYS[8], 'max-size')); if maxSize ~= nil and maxSize ~= 0 then     local currentTime = tonumber(ARGV[1]);     local lastAccessTimeSetName = KEYS[6];     redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[5]);     local cacheSize = tonumber(redis.call('hlen', KEYS[1]));     if cacheSize >= maxSize then         local lruItems = redis.call('zrange', lastAccessTimeSetName, 0, cacheSize - maxSize);         for index, lruItem in ipairs(lruItems) do             if lruItem and lruItem ~= ARGV[5] then                 local lruItemValue = redis.call('hget', KEYS[1], lruItem);                 redis.call('hdel', KEYS[1], lruItem);                 redis.call('zrem', KEYS[2], lruItem);                 redis.call('zrem', KEYS[3], lruItem);                 redis.call('zrem', lastAccessTimeSetName, lruItem);                 if lruItemValue ~= false then                 local removedChannelName = KEYS[7];                 local msg = struct.pack('Lc0Lc0', string.len(lruItem), lruItem, string.len(lruItemValue), lruItemValue);                 redis.call('publish', removedChannelName, msg); end;             end;         end;     end; end; local value = struct.pack('dLc0', ARGV[4], string.len(ARGV[6]), ARGV[6]); redis.call('hset', KEYS[1], ARGV[5], value); if insertable == true then local msg = struct.pack('Lc0Lc0', string.len(ARGV[5]), ARGV[5], string.len(ARGV[6]), ARGV[6]); redis.call('publish', KEYS[4], msg); return 1;else local msg = struct.pack('Lc0Lc0Lc0', string.len(ARGV[5]), ARGV[5], string.len(ARGV[6]), ARGV[6], string.len(val), val); redis.call('publish', KEYS[5], msg); return 0;end;" "8" "testRMapCache" "redisson__timeout__set:{testRMapCache}" "redisson__idle__set:{testRMapCache}" "redisson_map_cache_created:{testRMapCache}" "redisson_map_cache_updated:{testRMapCache}" "redisson__map_cache__last_access__set:{testRMapCache}" "redisson_map_cache_removed:{testRMapCache}" "{testRMapCache}:redisson_options" "1746173814893" "1746173817870" "0" "0" "\x04>\x03key" "\x04>\x05value"
1746173814.963279 [0 lua] "hget" "testRMapCache" "\x04>\x03key"
1746173814.963295 [0 lua] "zadd" "redisson__timeout__set:{testRMapCache}" "1746173817870" "\x04>\x03key"
1746173814.963315 [0 lua] "zrem" "redisson__idle__set:{testRMapCache}" "\x04>\x03key"
1746173814.963346 [0 lua] "hget" "{testRMapCache}:redisson_options" "max-size"
1746173814.963361 [0 lua] "hset" "testRMapCache" "\x04>\x03key" "\x00\x00\x00\x00\x00\x00\x00\x00\b\x00\x00\x00\x00\x00\x00\x00\x04>\x05value"
1746173814.963373 [0 lua] "publish" "redisson_map_cache_created:{testRMapCache}" "\x06\x00\x00\x00\x00\x00\x00\x00\x04>\x03key\b\x00\x00\x00\x00\x00\x00\x00\x04>\x05value"
// put运行的脚本
1746173818.078906 [0 192.168.188.1:39914] "EVAL" "local v = redis.call('hget', KEYS[1], ARGV[2]);local exists = false;if v ~= false then    local t, val = struct.unpack('dLc0', v);    local expireDate = 92233720368547758;    local expireDateScore = redis.call('zscore', KEYS[2], ARGV[2]);    if expireDateScore ~= false then        expireDate = tonumber(expireDateScore)    end;    if t ~= 0 then        local expireIdle = redis.call('zscore', KEYS[3], ARGV[2]);        if expireIdle ~= false then            expireDate = math.min(expireDate, tonumber(expireIdle))        end;    end;    if expireDate > tonumber(ARGV[1]) then        exists = true;    end;end;local value = struct.pack('dLc0', 0, string.len(ARGV[3]), ARGV[3]);redis.call('hset', KEYS[1], ARGV[2], value);local currentTime = tonumber(ARGV[1]);local lastAccessTimeSetName = KEYS[6];local maxSize = tonumber(redis.call('hget', KEYS[8], 'max-size'));if exists == false then    if maxSize ~= nil and maxSize ~= 0 then        redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[2]);        local cacheSize = tonumber(redis.call('hlen', KEYS[1]));        if cacheSize > maxSize then            local lruItems = redis.call('zrange', lastAccessTimeSetName, 0, cacheSize - maxSize - 1);            for index, lruItem in ipairs(lruItems) do                if lruItem and lruItem ~= ARGV[2] then                    local lruItemValue = redis.call('hget', KEYS[1], lruItem);                    redis.call('hdel', KEYS[1], lruItem);                    redis.call('zrem', KEYS[2], lruItem);                    redis.call('zrem', KEYS[3], lruItem);                    redis.call('zrem', lastAccessTimeSetName, lruItem);                    if lruItemValue ~= false then                     local removedChannelName = KEYS[7];                    local msg = struct.pack('Lc0Lc0', string.len(lruItem), lruItem, string.len(lruItemValue), lruItemValue);                    redis.call('publish', removedChannelName, msg);end;                 end;            end        end;    end;    local msg = struct.pack('Lc0Lc0', string.len(ARGV[2]), ARGV[2], string.len(ARGV[3]), ARGV[3]);    redis.call('publish', KEYS[4], msg);    return nil;else    if maxSize ~= nil and maxSize ~= 0 then        redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[2]);    end;end;local t, val = struct.unpack('dLc0', v);local msg = struct.pack('Lc0Lc0Lc0', string.len(ARGV[2]), ARGV[2], string.len(ARGV[3]), ARGV[3], string.len(val), val);redis.call('publish', KEYS[5], msg);return val;" "8" "testRMapCache" "redisson__timeout__set:{testRMapCache}" "redisson__idle__set:{testRMapCache}" "redisson_map_cache_created:{testRMapCache}" "redisson_map_cache_updated:{testRMapCache}" "redisson__map_cache__last_access__set:{testRMapCache}" "redisson_map_cache_removed:{testRMapCache}" "{testRMapCache}:redisson_options" "1746173818075" "\x04>\x03key" "\x04>\x0canotherValue"
1746173818.079148 [0 lua] "hget" "testRMapCache" "\x04>\x03key"
1746173818.079162 [0 lua] "zscore" "redisson__timeout__set:{testRMapCache}" "\x04>\x03key"
1746173818.079181 [0 lua] "hset" "testRMapCache" "\x04>\x03key" "\x00\x00\x00\x00\x00\x00\x00\x00\x0f\x00\x00\x00\x00\x00\x00\x00\x04>\x0canotherValue"
1746173818.079190 [0 lua] "hget" "{testRMapCache}:redisson_options" "max-size"
1746173818.079197 [0 lua] "publish" "redisson_map_cache_created:{testRMapCache}" "\x06\x00\x00\x00\x00\x00\x00\x00\x04>\x03key\x0f\x00\x00\x00\x00\x00\x00\x00\x04>\x0canotherValue"

// get运行的脚本
1746173818.088388 [0 192.168.188.1:39882] "EVAL" "local value = redis.call('hget', KEYS[1], ARGV[2]); if value == false then return nil; end; local t, val = struct.unpack('dLc0', value); local expireDate = 92233720368547758; local expireDateScore = redis.call('zscore', KEYS[2], ARGV[2]); if expireDateScore ~= false then expireDate = tonumber(expireDateScore) end; if t ~= 0 then local expireIdle = redis.call('zscore', KEYS[3], ARGV[2]); if expireIdle ~= false then if tonumber(expireIdle) > tonumber(ARGV[1]) then redis.call('zadd', KEYS[3], t + tonumber(ARGV[1]), ARGV[2]); end; expireDate = math.min(expireDate, tonumber(expireIdle)) end; end; if expireDate <= tonumber(ARGV[1]) then return nil; end; local maxSize = tonumber(redis.call('hget', KEYS[5], 'max-size')); if maxSize ~= nil and maxSize ~= 0 then    redis.call('zadd', KEYS[4], tonumber(ARGV[1]), ARGV[2]); end; return val; " "5" "testRMapCache" "redisson__timeout__set:{testRMapCache}" "redisson__idle__set:{testRMapCache}" "redisson__map_cache__last_access__set:{testRMapCache}" "{testRMapCache}:redisson_options" "1746173818080" "\x04>\x03key"

1746173818.088480 [0 lua] "hget" "testRMapCache" "\x04>\x03key"
1746173818.088491 [0 lua] "zscore" "redisson__timeout__set:{testRMapCache}" "\x04>\x03key"

分析一下lua脚本

fastput 核心lua脚本

KEYS[1] = "testRMapCache"              -- redis hash key
KEYS[2] = "redisson__timeout__set:{testRMapCache}"  -- TTL 过期时间有序集合
KEYS[3] = "redisson__idle__set:{testRMapCache}"     -- Idle 过期时间有序集合
KEYS[4] = "redisson_map_cache_created:{testRMapCache}"  -- 创建事件频道
KEYS[5] = "redisson_map_cache_updated:{testRMapCache}"  -- 更新事件频道
KEYS[6] = "redisson__map_cache__last_access__set:{testRMapCache}"  -- 最后访问时间集合（LRU）
KEYS[7] = "redisson_map_cache_removed:{testRMapCache}"  -- 移除事件频道
KEYS[8] = "{testRMapCache}:redisson_options"        -- 缓存配置（如 max-size）

ARGV[1] = "1746173814893"     -- 当前时间戳
ARGV[2] = "1746173817870"     -- TTL 过期时间
ARGV[3] = "0"                 -- Idle 过期时间
ARGV[4] = "0"                 -- 最大闲置时间
ARGV[5] = "\x04>\x03key"      -- 键名
ARGV[6] = "\x04>\x05value"    -- 值

-- 是否是新增的，用于后面的pubsub通知
local insertable = false;
local value = redis.call('hget', KEYS[1], ARGV[5]);
local t, val;
if value == false then
    insertable = true;
else
    t, val = struct.unpack('dLc0', value);
    local expireDate = 92233720368547758;
    local expireDateScore = redis.call('zscore', KEYS[2], ARGV[5]);
    if expireDateScore ~= false then expireDate = tonumber(expireDateScore) end
    if t ~= 0 then
        local expireIdle = redis.call('zscore', KEYS[3], ARGV[5]);
        if expireIdle ~= false then
            expireDate = math.min(expireDate, tonumber(expireIdle))
        end
    end
    if expireDate <= tonumber(ARGV[1]) then insertable = true; end
end

-- 写入ttl过期时间
if tonumber(ARGV[2]) > 0 then
    redis.call('zadd', KEYS[2], ARGV[2], ARGV[5]);
else
    redis.call('zrem', KEYS[2], ARGV[5]);
end

-- 写入idle过期时间
if tonumber(ARGV[3]) > 0 then
    redis.call('zadd', KEYS[3], ARGV[3], ARGV[5]);
else
    redis.call('zrem', KEYS[3], ARGV[5]);
end

-- 测试代码不涉及最大容量，这部分lru淘汰策略不执行，和bug无关
local maxSize = tonumber(redis.call('hget', KEYS[8], 'max-size'));
if maxSize ~= nil and maxSize ~= 0 then
    local currentTime = tonumber(ARGV[1]);
    local lastAccessTimeSetName = KEYS[6];
    redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[5]);
    local cacheSize = tonumber(redis.call('hlen', KEYS[1]));
    if cacheSize >= maxSize then
        local lruItems = redis.call('zrange', lastAccessTimeSetName, 0,
                                    cacheSize - maxSize);
        for index, lruItem in ipairs(lruItems) do
            if lruItem and lruItem ~= ARGV[5] then
                local lruItemValue = redis.call('hget', KEYS[1], lruItem);
                redis.call('hdel', KEYS[1], lruItem);
                redis.call('zrem', KEYS[2], lruItem);
                redis.call('zrem', KEYS[3], lruItem);
                redis.call('zrem', lastAccessTimeSetName, lruItem);
                if lruItemValue ~= false then
                    local removedChannelName = KEYS[7];
                    local msg = struct.pack('Lc0Lc0', string.len(lruItem),
                                            lruItem, string.len(lruItemValue),
                                            lruItemValue);
                    redis.call('publish', removedChannelName, msg);
                end
            end
        end
    end
end

-- 写入value，value前面拼接了一个idle过期时间
local value = struct.pack('dLc0', ARGV[4], string.len(ARGV[6]), ARGV[6]);
redis.call('hset', KEYS[1], ARGV[5], value);

-- pubsub 给listener用的，和bug没什么关系
if insertable == true then
    local msg = struct.pack('Lc0Lc0', string.len(ARGV[5]), ARGV[5],
                            string.len(ARGV[6]), ARGV[6]);
    redis.call('publish', KEYS[4], msg);
    return 1;
else
    local msg = struct.pack('Lc0Lc0Lc0', string.len(ARGV[5]), ARGV[5],
                            string.len(ARGV[6]), ARGV[6], string.len(val), val);
    redis.call('publish', KEYS[5], msg);
    return 0;
end

put 核心lua脚本

KEYS[1] = "testRMapCache"                          -- redis hash key
KEYS[2] = "redisson__timeout__set:{testRMapCache}"  -- TTL 过期时间zset
KEYS[3] = "redisson__idle__set:{testRMapCache}"     -- Idle 过期时间zset
KEYS[4] = "redisson_map_cache_created:{testRMapCache}"  -- 创建事件频道
KEYS[5] = "redisson_map_cache_updated:{testRMapCache}"  -- 更新事件频道
KEYS[6] = "redisson__map_cache__last_access__set:{testRMapCache}" -- 最后访问时间集合（LRU）
KEYS[7] = "redisson_map_cache_removed:{testRMapCache}"  -- 移除事件频道
KEYS[8] = "{testRMapCache}:redisson_options"        -- 缓存配置（max-size）

ARGV[1] = "1746173818075"         -- 当前时间戳
ARGV[2] = "\x04>\x03key"          -- key
ARGV[3] = "\x04>\x0canotherValue" -- value

local v = redis.call('hget', KEYS[1], ARGV[2]);
local exists = false;

-- 判断是否已存在，主要是给后面lru淘汰策略使用，和bug暂时无关
if v ~= false then
    local t, val = struct.unpack('dLc0', v);
    local expireDate = 92233720368547758;
    local expireDateScore = redis.call('zscore', KEYS[2], ARGV[2]);
    if expireDateScore ~= false then expireDate = tonumber(expireDateScore) end
    if t ~= 0 then
        local expireIdle = redis.call('zscore', KEYS[3], ARGV[2]);
        if expireIdle ~= false then
            expireDate = math.min(expireDate, tonumber(expireIdle))
        end
    end
    if expireDate > tonumber(ARGV[1]) then exists = true; end
end
-- value前面拼接了过期时间，不过这个地方不涉及过期时间就拼接了一个0上去
local value = struct.pack('dLc0', 0, string.len(ARGV[3]), ARGV[3]);
redis.call('hset', KEYS[1], ARGV[2], value);

local currentTime = tonumber(ARGV[1]);
local lastAccessTimeSetName = KEYS[6];
local maxSize = tonumber(redis.call('hget', KEYS[8], 'max-size'));
-- 测试代码不涉及最大容量，这部分lru淘汰策略不执行，和bug无关
if exists == false then
    if maxSize ~= nil and maxSize ~= 0 then
        redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[2]);
        local cacheSize = tonumber(redis.call('hlen', KEYS[1]));
        if cacheSize > maxSize then
            local lruItems = redis.call('zrange', lastAccessTimeSetName, 0,
                                        cacheSize - maxSize - 1);
            for index, lruItem in ipairs(lruItems) do
                if lruItem and lruItem ~= ARGV[2] then
                    local lruItemValue = redis.call('hget', KEYS[1], lruItem);
                    redis.call('hdel', KEYS[1], lruItem);
                    redis.call('zrem', KEYS[2], lruItem);
                    redis.call('zrem', KEYS[3], lruItem);
                    redis.call('zrem', lastAccessTimeSetName, lruItem);
                    if lruItemValue ~= false then
                        local removedChannelName = KEYS[7];
                        local msg = struct.pack('Lc0Lc0', string.len(lruItem),
                                                lruItem,
                                                string.len(lruItemValue),
                                                lruItemValue);
                        redis.call('publish', removedChannelName, msg);
                    end
                end
            end
        end
    end
    local msg = struct.pack('Lc0Lc0', string.len(ARGV[2]), ARGV[2],
                            string.len(ARGV[3]), ARGV[3]);
    redis.call('publish', KEYS[4], msg);
    return nil;
else
    -- 刷新一下 最近访问时间
    if maxSize ~= nil and maxSize ~= 0 then
        redis.call('zadd', lastAccessTimeSetName, currentTime, ARGV[2]);
    end
end

-- pubsub通知，和bug无关
local t, val = struct.unpack('dLc0', v);
local msg = struct.pack('Lc0Lc0Lc0', string.len(ARGV[2]), ARGV[2],
                        string.len(ARGV[3]), ARGV[3], string.len(val), val);
redis.call('publish', KEYS[5], msg);
return val;

get 核心lua脚本

KEYS[1]	testRMapCache	         -- redis hash key
KEYS[2]	redisson__timeout__set:{testRMapCache}	-- TTL 过期时间 zset
KEYS[3]	redisson__idle__set:{testRMapCache}	    -- Idle 过期时间 zset
KEYS[4]	redisson__map_cache__last_access__set:{testRMapCache}	-- 最后访问时间集合（LRU）
KEYS[5]	{testRMapCache}:redisson_options	-- 缓存配置（如 max-size）

ARGV[1]	1746173818080	-- 当前时间戳
ARGV[2]	\x04>\x03key	-- key

-- 查询具体值
local value = redis.call('hget', KEYS[1], ARGV[2]);
if value == false then return nil; end
local t, val = struct.unpack('dLc0', value);
-- 计算过期时间
local expireDate = 92233720368547758;
local expireDateScore = redis.call('zscore', KEYS[2], ARGV[2]);
if expireDateScore ~= false then expireDate = tonumber(expireDateScore) end
if t ~= 0 then
    local expireIdle = redis.call('zscore', KEYS[3], ARGV[2]);
    if expireIdle ~= false then
        if tonumber(expireIdle) > tonumber(ARGV[1]) then
            redis.call('zadd', KEYS[3], t + tonumber(ARGV[1]), ARGV[2]);
        end
        expireDate = math.min(expireDate, tonumber(expireIdle))
    end
end

-- 如果过期了则直接返回null
if expireDate <= tonumber(ARGV[1]) then return nil; end
local maxSize = tonumber(redis.call('hget', KEYS[5], 'max-size'));
if maxSize ~= nil and maxSize ~= 0 then
    redis.call('zadd', KEYS[4], tonumber(ARGV[1]), ARGV[2]);
end
return val;

问题定位

问题看出来了，重新分析一下测试代码

    public void test() {
        RMapCache<String, String> testRMapCache = redissonClient.getMapCache("testRMapCache");
        // 往testRMapCache这个hash中写入了  key-value
        // ttl zset中也会写入 3s 后的时间戳
        testRMapCache.fastPut("key", "value", 3, TimeUnit.SECONDS);
        try {
            //等缓存过期
            Thread.sleep(3100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 往缓存写入另外一个值
        testRMapCache.put("key", "anotherValue");
        // 上面一行代码写入值后，此时ttl zset中的过期时间仍然存在，再去拿肯定拿不出来
        // 然后解释一下为什么是偶现
        // RMapCache有一个定时任务会去清理无效数据（间隔时间最短5s），在上面等待缓存过期期间如果数据被清理了，那么就一切正常
        String result = testRMapCache.get("key");
        System.out.println("result: " + result);// null
    }

解决方案

上面的代码写法有点不对称，先写入一个带过期时间的key-value，后面又写入不带过期时间的key-value，这里可以根据业务需求直接改成统一带过期时间，或者都不带过期时间的
升级redisson到3.13.5以上的版本

在redisson 3.13.5版本中，这个bug被修复，现在再看看redisson官方是怎么修改这个bug的

Fixed - fail to insert key with TTL = 0 if the same key was previousl… · redisson/redisson@ccfa4ed

这段代码就是在执行put的时候，直接干掉idle 和 ttl 过期时间对应zset中的数据

小结

本文主要分析了特定用法下redisson 缓存读不出来的bug，其实分析的方式并不是特别好，在抓redis monitor日志的时候，经常会被redisson自带的定时任务给干扰，有这个排查干扰的时间，不如直接去看源码，这样估计能更快定位出来，这次就当是踩坑了，后面有时间再写几篇文章继续分析一下RMapCache这个工具。

菜单

分享

测试代码

redis monitor 监听

分析一下lua脚本

问题定位

解决方案

小结