java - 在 Neo4j Desktop 中启用 Java Flight Recorder

Question

我试图在使用 Neo4j Desktop 运行 Cypher 查询时启用 Java Flight Recorder 每 10 秒收集一次线程转储。但在 Neo4j 桌面的“设置”选项卡(配置文件)中，推荐的飞行记录器选项无法识别，并在启动过程中抛出错误。

我正在使用 Oracle JDK 11。

这些是我在文件中输入的命令 -

# flight recorder settings
dbms.jvm.additional=-XX:+UnlockCommercialFeatures
dbms.jvm.additional=-XX:+FlightRecorder
dbms.jvm.additional=-XX:FlightRecorderOptions=stackdepth=500
dbms.jvm.additional=-XX:+UnlockDiagnosticVMOptions
dbms.jvm.additional=-XX:+DebugNonSafepoints

当我启动数据库时，这些会抛出错误 -

Active database: graph.db
Directories in use:
  home:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3
  config:       /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/conf
  logs:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/logs
  plugins:      /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/plugins
  import:       /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/import
  data:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/data
  certificates: /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/certificates
  run:          /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/run
Starting Neo4j.
Unrecognized VM option 'UnlockCommercialFeatures'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
Active database: graph.db
Directories in use:
  home:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3
  config:       /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/conf
  logs:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/logs
  plugins:      /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/plugins
  import:       /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/import
  data:         /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/data
  certificates: /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/certificates
  run:          /Users/manishgiri/Library/Application Support/Neo4j Desktop/Application/neo4jDatabases/database-4efa4b3e-50bc-46fa-90b2-ee6df8205205/installation-3.5.3/run
Starting Neo4j.
Unrecognized VM option 'FlightRecorder'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

我通过在另一个简单程序上进行测试来验证 Flight Recorder 确实可以在我的计算机上运行 -

java -XX:+UnlockCommercialFeatures -XX:+FlightRecorder -XX:StartFlightRecording=duration=120s,filename=myrecording.jfr OOMEGenerator

此命令运行良好并成功生成录音。

是否有其他方法可以在配置文件中启用飞行记录器设置？

Answer 1

Neo4j Desktop 包含来自 Azul 的 Java 虚拟机，该虚拟机基于 OpenJDK，无法识别 -XX:+UnlockCommercialFeatures 标志。

由于 Flight Recorder 已开源(JDK 11)，因此不再需要该标志。 Oracle JDK 将忽略该标志。

最简单的方法就是删除 -XX:+UnlockCommercialFeatures 标志。

如果这不起作用，即它提示 -XX:+FlightRecorder 或 -XX:StartFlightRecording，可能是因为 Neo4j Desktop 附带早期版本的 Azul，该版本不支持 Flight Recorder。

如果是这种情况，你必须切换JDK。

(您还可以删除 -XX:+FlightRecorder，因为自 Oracle JDK 8u40 之前的版本以来不再需要此标志)