[jira] [Created] (TINKERPOP-2767) Repeat Out Times traversal hangs indefinitely on first execution

["Simon Zhao (Jira)" <ji...@apache.org>]

Simon Zhao created TINKERPOP-2767:
-------------------------------------

             Summary: Repeat Out Times traversal hangs indefinitely on first execution
                 Key: TINKERPOP-2767
                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2767
             Project: TinkerPop
          Issue Type: Bug
    Affects Versions: 3.5.3
         Environment: Windows 10
            Reporter: Simon Zhao


Originally encountered when fixing [TINKERPOP-2754|[https://issues.apache.org/jira/projects/TINKERPOP/issues/TINKERPOP-2754?filter=allopenissues].]

 

The following traversal in JS seems to cause hanging the first time you run it on a newly launched gremlin-server (3.5.3) via docker

 
{{await g.V('1').repeat(_.out()).times(1500).next();}}
 
The same hanging occurs in gremlin-go. 
 
{{{}_, err = g.With("evaluationTimeout", 1000).V("1").Repeat(gremlingo.T__.Out()).Times(int32(1500)).Next(){}}}{{{}{}}}

 

The timeout is optional, but indicates that something is going wrong since it is not returning. Interestingly enough, if the timeout is very low, then it won't hang because it will say the timeout was exceeded. This indicates that if the traversal is completed within the timeout, it's just not returning for some reason on the first call.

 

If you were to write a script and invoke this snippet of code, it will hang. If you forcefully terminate the script and rerun it, then it doesn't hang.

 

main.go
{code:java}
package main

import (
   gremlingo "github.com/apache/tinkerpop/gremlin-go/v3/driver"
   "log"
)

func main() {
   driver, err := gremlingo.NewDriverRemoteConnection("ws://localhost:45940/gremlin")
   if err != nil {
      log.Print("Err creating DRC")
      return
   }
   defer driver.Close()

   log.Println("Start")
   g := gremlingo.Traversal_().WithRemote(driver)
   LABEL := "test"
   _, err = g.V().HasLabel(LABEL).Drop().Next()
   _, err = g.AddV(LABEL).Property(gremlingo.T.Id, "1").Next()
   _, err = g.AddV(LABEL).Property(gremlingo.T.Id, "2").Next()
   _, err = g.AddE(LABEL).From(gremlingo.T__.V("1")).To(gremlingo.T__.V("2")).Property(gremlingo.T.Id, "e1").Next()
   _, err = g.AddE(LABEL).From(gremlingo.T__.V("2")).To(gremlingo.T__.V("1")).Property(gremlingo.T.Id, "e2").Next()
   if err != nil {
      log.Println("Error during setup")
      return
   }
   log.Println("Start the problematic traversal")
   _, err = g.With("evaluationTimeout", 1000).V("1").Repeat(gremlingo.T__.Out()).Times(int32(1500)).Next()
   if err != nil {
      log.Println("Error with the problematic traversal, but we didn't hang")
      return
   }
   log.Println("End")
} {code}



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