[Bug] java.lang.ClassCastException: class org.apache.hugegraph.task.DistributedTaskScheduler cannot be cast to class org.apache.hugegraph.task.StandardTaskScheduler

[hexuxu110]

Bug Type (问题类型)

None

Before submit

• 我已经确认现有的 Issues 与 FAQ 中没有相同 / 重复问题 (I have confirmed and searched that there are no similar problems in the historical issue and documents)

Environment (环境信息)

• Server Version: 1.5.0 (Apache Release Version)
• Backend: Hstore x nodes, HDD or SSD
• OS: xx CPUs, xx G RAM, Ubuntu 2x.x / CentOS 7.x
• Data Size: xx vertices, xx edges

Expected & Actual behavior (期望与实际表现)

2025-07-28 17:56:05 [pool-15-thread-1] [ERROR] o.a.h.t.TaskManager - Exception occurred when change to master role
java.lang.ClassCastException: class org.apache.hugegraph.task.DistributedTaskScheduler cannot be cast to class org.apache.hugegraph.task.StandardTaskScheduler (org.apache.hugegraph.task.DistributedTaskScheduler and org.apache.hugegraph.task.StandardTaskScheduler are in unnamed module of loader 'app')
at org.apache.hugegraph.task.TaskManager.onAsRoleMaster(TaskManager.java:359) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleListener.onAsRoleMaster(StandardRoleListener.java:47) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleElectionStateMachine.apply(StandardRoleElectionStateMachine.java:75) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleElectionStateMachine.lambda$start$0(StandardRoleElectionStateMachine.java:60) ~[hugegraph-core-1.5.0.jar:1.5.0]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[?:?]
at java.lang.Thread.run(Thread.java:829) [?:?]
2025-07-28 17:56:05 [pool-15-thread-1] [ERROR] o.a.h.m.StandardRoleListener - Server server-1 exception occurred
java.lang.ClassCastException: class org.apache.hugegraph.task.DistributedTaskScheduler cannot be cast to class org.apache.hugegraph.task.StandardTaskScheduler (org.apache.hugegraph.task.DistributedTaskScheduler and org.apache.hugegraph.task.StandardTaskScheduler are in unnamed module of loader 'app')
at org.apache.hugegraph.task.TaskManager.onAsRoleMaster(TaskManager.java:359) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleListener.onAsRoleMaster(StandardRoleListener.java:47) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleElectionStateMachine.apply(StandardRoleElectionStateMachine.java:75) ~[hugegraph-core-1.5.0.jar:1.5.0]
at org.apache.hugegraph.masterelection.StandardRoleElectionStateMachine.lambda$start$0(StandardRoleElectionStateMachine.java:60) ~[hugegraph-core-1.5.0.jar:1.5.0]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[?:?]
at java.lang.Thread.run(Thread.java:829) [?:?]

Vertex/Edge example (问题点 / 边数据举例)

我的rest配置

restserver.url=http://0.0.0.0:8081
gremlinserver.url=http://127.0.0.1:8181

graphs=./conf/graphs

# ????
auth.authenticator=org.apache.hugegraph.auth.StandardAuthenticator
auth.admin_token=54702de7-b89e-4a80-817c-b3020e7323a0
auth.user_tokens=user0:d75469f7-90e8-45fd-9012-7801cc0d9df6

rpc.server_host=127.0.0.1
rpc.server_port=8091

rpc.remote_url=127.0.0.1:8091
rpc.client_connect_timeout=60
rpc.client_reconnect_period=15
rpc.client_read_timeout=60
rpc.client_retries=5
rpc.client_load_balancer=consistentHash


log.slow_query_threshold=1000

server.id=server-1
server.role=master

Schema [VertexLabel, EdgeLabel, IndexLabel] (元数据结构)

[dosubot]

你的报错是因为 HugeGraph 在切换为 master 角色时，代码把 DistributedTaskScheduler 强制转换成了 StandardTaskScheduler，但实际当前环境下用的是 DistributedTaskScheduler，导致 ClassCastException。这通常出现在分布式或 HStore+PD 场景下，配置和代码对调度器类型的预期不一致。

HugeGraph 1.5.0 在 HStore+PD 场景下，集群调度完全由 PD 负责，master/worker 机制和 server.role 配置已经废弃，不再生效。如果你配置了 server.role=master，或者以“传统”分布式方式启动，可能会触发这类类型转换错误。建议：

1. 检查你的部署模式和 backend 配置，确认是否为 HStore+PD。如果是，去掉 server.role 相关配置，确保所有节点配置一致，完全交由 PD 管理集群角色和任务调度。
2. 如果不是 PD 场景，确保 schedulerType、server.role 等配置和实际部署模式一致，避免混用分布式和本地调度逻辑。
3. 这个问题在社区有类似反馈，属于 1.5.0 版本的已知类型安全隐患，建议关注后续版本修复或社区讨论进展。相关讨论和说明

如需进一步排查，建议贴出 backend 相关配置和 PD 相关参数，确认集群实际运行模式。

To reply, just mention @dosu.

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[hexuxu110]

那我部署1.5.0分布式版本(底层使用hstore)这块报错，影响我服务吗

[dosubot]

这个报错不会导致整个 HugeGraph 服务直接崩溃，核心的图存储和 PD 分布式协调功能不会受影响，服务还能正常读写数据。但凡是依赖旧 master/worker 机制的功能（比如定时任务、系统级调度任务）会因为这个异常无法正常工作，相关任务不会被调度或执行，且不会有明显提示。根本原因是 1.5.0 分布式（PD/HStore）模式下已经废弃了 master/worker 逻辑，配置或代码路径如果还触发了这部分逻辑就会报错。

建议检查 rest-server.properties 等配置，去掉 server.role、server.id 等和 master/worker 相关的参数，确保只用 PD 分布式模式的推荐配置。详细原理和类似问题可以参考 issue #2833。

To reply, just mention @dosu.

---

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[hexuxu110]

我的配置文件rest
restserver.url=http://0.0.0.0:8081
gremlinserver.url=http://127.0.0.1:8181

graphs=./conf/graphs

????

auth.authenticator=org.apache.hugegraph.auth.StandardAuthenticator

auth.admin_token=54702de7-b89e-4a80-817c-b3020e7323a0
auth.user_tokens=user0:d75469f7-90e8-45fd-9012-7801cc0d9df6

rpc.server_host=127.0.0.1
rpc.server_port=8091

rpc.remote_url=127.0.0.1:8091
rpc.client_connect_timeout=60
rpc.client_reconnect_period=15
rpc.client_read_timeout=60
rpc.client_retries=5
rpc.client_load_balancer=consistentHash

log.slow_query_threshold=1000

但还是会报这个错误

[koi2000]

hugegraph.properties文件中task.scheduler_type在分布式部署时需要设置为distributed
目前的hugegraph.properties是如何设置的呢

[hexuxu110]

backend=hstore
serializer=binary

store=hugegraph
task.scheduler_type=distributed

pd config

#pd.peers=127.0.0.1:8686
pd.peers=127.0.0.1:8686,127.0.0.1:8687,127.0.0.1:8688

search config

search.text_analyzer=jieba
search.text_analyzer_mode=INDEX

rocksdb backend config

rocksdb.data_path=/path/to/disk
rocksdb.wal_path=/path/to/disk