Error for `h2o_start()` without java installed

[hfrick]

When I run h2o_start() without things installed/configured correctly, I do get

> h2o_start()
The operation couldn’t be completed. Unable to locate a Java Runtime.
Please visit http://www.java.com for information on installing Java.

but then it just hangs there. It would be nice if that threw an error instead.

[qiushiyan]

Thanks @hfrick for reporting this. I didn't see this error message after searching the h2o codebase. I found this function .h2o.checkJava to be used for determining java installation though, which relies on Sys.getenv('JAVA_HOME') and Sys.which('java'). After I cleaned PATH I got the error

withr::with_path(
  getwd(), 
  {
    print(c(Sys.which("java"), Sys.getenv("JAVA_HOME")))
    agua::h2o_start()
  }, 
  action = "replace"
)
#> java      
#>   ""   ""
#> Registered S3 method overwritten by 'agua':
#>   method        from     
#>   tidy.workflow workflows
#> Error in .h2o.checkJava(): Cannot find Java. Please install the latest JRE from
#> https://www.oracle.com/technetwork/java/javase/downloads/index.html

^{Created on 2022-11-05 with reprex v2.0.2}

[hfrick]

Ah, thanks for this! So I do have java installed but I do not have JAVA_HOMEset. I put your example in a reprex and with the working directory as the path, I get the same as you. If I don't set that, as in the first part of the reprex below, it also errors but it only does so eventually. When I ran that first part interactively, I've never been patient enough to wait...

print(c(Sys.which("java"), Sys.getenv("JAVA_HOME")))
#>            java                 
#> "/usr/bin/java"              ""
agua::h2o_start()
#> Registered S3 method overwritten by 'agua':
#>   method        from     
#>   tidy.workflow workflows
#> Warning in system2(command, "-version", stdout = TRUE, stderr = TRUE): running
#> command ''/usr/bin/java' -version 2>&1' had status 1
#> Error in h2o::h2o.init(): H2O failed to start, stopping execution.

withr::with_path(
  getwd(), 
  {
    print(c(Sys.which("java"), Sys.getenv("JAVA_HOME")))
    agua::h2o_start()
  }, 
  action = "replace"
)
#> java      
#>   ""   ""
#> Error in .h2o.checkJava(): Cannot find Java. Please install the latest JRE from
#> https://www.oracle.com/technetwork/java/javase/downloads/index.html

^{Created on 2022-11-07 with reprex v2.0.2}

[qiushiyan]

What is the output if you run /usr/bin/java -version from the command line? Seems this fails to locate java's version. The hanging is caused by https://github.com/h2oai/h2o-3/blob/master/h2o-r/h2o-package/R/connection.R#L217-L223 which tries to wait for 60 seconds before connection is established, agua could probabably do an early stop or add messages if previous commands fail.

[hfrick]

yup, looks like it can't locate it

 % /usr/bin/java -version
The operation couldn’t be completed. Unable to locate a Java Runtime.
Please visit http://www.java.com for information on installing Java.

an alternative to failing earlier than 60 seconds could also be telling the user that this step can take up to 60 seconds

[qiushiyan]

fixed by 9922d26

[github-actions[bot]]

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