[ 
https://issues.apache.org/jira/browse/TINKERPOP-3087?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

David Bennington updated TINKERPOP-3087:
----------------------------------------
    Description: 
Ocasionally, I get the following panic in the gremlin-go driver:

 
{noformat}
10:22:39.895 <successfully added a vertex to janusgraph>
10:22:44.487 panic: runtime error: invalid memory address or nil pointer 
dereference
10:22:44.487 [signal SIGSEGV: segmentation violation code=0x1 addr=0x78 
pc=0x11fdd16]
10:22:44.487 
10:22:44.487 goroutine 275 [running]:
10:22:44.487 
github.com/apache/tinkerpop/gremlin-go/v3/driver.(*gremlinServerWSProtocol).responseHandler(0xc0006be6c0,
 0xc0001dfc60, {{0x9, 0xf6, 0x33, 0x7f, 0x19, 0x16, 0x4e, 0xc9, ...}, ...})
10:22:44.487 
/go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:116
 +0x7d6
10:22:44.487 
github.com/apache/tinkerpop/gremlin-go/v3/driver.(*gremlinServerWSProtocol).readLoop(0xc0006be6c0,
 0xc0001dfc60, 0xc0001dfca0)
10:22:44.487 
/go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:82
 +0x272
10:22:44.487 created by 
github.com/apache/tinkerpop/gremlin-go/v3/driver.newGremlinServerWSProtocol in 
goroutine 272
10:22:44.487 
/go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:197
 +0x23a{noformat}
I can't reliably reproduce, it's never happened locally. It's occurred just 
after doing some work in the logs above, but it's also happened after a period 
of doing nothing.

 

First glance looks like it's a nil being returned from the `resultSets` 
synchronizedMap, something getting in and removing it, which should only happen 
when the `channelResultSet` itself is closed? Seems like a race condition to me.

I think the sensible way to handle this, if it is what I suspect (I've no proof 
yet), would be to
 * Store a reference to the ResultSet when first loading it in responseHandler
 * Make `channelResultSet` discard modifications after close OR
 * responseHandler needs to aquire the `channelMutex` somehow for the duration 
of modifications (I think I prefer this, it's more obvious to what's happening)

I did try and get the project tests to run, but it's been _years_ since I've 
had to use maven and I can't seem to find a good idiots guide to working with 
the project from a non java POV - I need to know how to build the docker images 
the tests require. If someone could help me get started I'd be more than happy 
to contribute a PR (although given the nature, a reliable test may be hard to 
write).

As it stands, I'm probably going to modify my fork and mod replace, see if a 
fix would actually work in my deployments.

  was:
Ocasionally, I get the following panic in the gremlin-go driver:

 

```
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}39.895{color}{color:#000000}
 <{color}{color:#001080}successfully{color}{color:#000000} 
{color}{color:#001080}added{color}{color:#000000} 
{color}{color:#001080}a{color}{color:#000000} 
{color}{color:#001080}vertex{color}{color:#000000} 
{color}{color:#001080}to{color}{color:#000000} 
{color}{color:#001080}janusgraph{color}{color:#000000}>{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 {color}{color:#001080}panic{color}{color:#000000}: 
{color}{color:#001080}runtime{color}{color:#000000} 
{color}{color:#267f99}error{color}{color:#000000}: 
{color}{color:#001080}invalid{color}{color:#000000} 
{color}{color:#001080}memory{color}{color:#000000} 
{color}{color:#001080}address{color}{color:#000000} 
{color}{color:#001080}or{color}{color:#000000} 
{color}{color:#0000ff}nil{color}{color:#000000} 
{color}{color:#001080}pointer{color}{color:#000000} 
{color}{color:#001080}dereference{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 [{color}{color:#001080}signal{color}{color:#000000} 
{color}{color:#001080}SIGSEGV{color}{color:#000000}: 
{color}{color:#001080}segmentation{color}{color:#000000} 
{color}{color:#001080}violation{color}{color:#000000} 
{color}{color:#001080}code{color}{color:#000000}={color}{color:#098658}0x1{color}{color:#000000}
 
{color}{color:#001080}addr{color}{color:#000000}={color}{color:#098658}0x78{color}{color:#000000}
 
{color}{color:#001080}pc{color}{color:#000000}={color}{color:#098658}0x11fdd16{color}{color:#000000}]{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 {color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 {color}{color:#001080}goroutine{color}{color:#000000} 
{color}{color:#098658}275{color}{color:#000000} 
[{color}{color:#001080}running{color}{color:#000000}]:{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 
{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}.(*{color}{color:#267f99}gremlinServerWSProtocol{color}{color:#000000}).{color}{color:#795e26}responseHandler{color}{color:#000000}({color}{color:#098658}0xc0006be6c0{color}{color:#000000},
 {color}{color:#098658}0xc0001dfc60{color}{color:#000000}, 
{{{color}{color:#098658}0x9{color}{color:#000000}, 
{color}{color:#098658}0xf6{color}{color:#000000}, 
{color}{color:#098658}0x33{color}{color:#000000}, 
{color}{color:#098658}0x7f{color}{color:#000000}, 
{color}{color:#098658}0x19{color}{color:#000000}, 
{color}{color:#098658}0x16{color}{color:#000000}, 
{color}{color:#098658}0x4e{color}{color:#000000}, 
{color}{color:#098658}0xc9{color}{color:#000000}, ...}, ...}){color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 
/{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}pkg{color}{color:#000000}/{color}{color:#001080}mod{color}{color:#000000}/{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}@{color}{color:#001080}v3{color}{color:#000000}.{color}{color:#098658}7.1{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}/{color}{color:#001080}protocol{color}{color:#000000}.{color}{color:#af00db}go{color}{color:#000000}:{color}{color:#098658}116{color}{color:#000000}
 +{color}{color:#098658}0x7d6{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 
{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}.(*{color}{color:#267f99}gremlinServerWSProtocol{color}{color:#000000}).{color}{color:#795e26}readLoop{color}{color:#000000}({color}{color:#098658}0xc0006be6c0{color}{color:#000000},
 {color}{color:#098658}0xc0001dfc60{color}{color:#000000}, 
{color}{color:#098658}0xc0001dfca0{color}{color:#000000}){color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 
/{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}pkg{color}{color:#000000}/{color}{color:#001080}mod{color}{color:#000000}/{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}@{color}{color:#001080}v3{color}{color:#000000}.{color}{color:#098658}7.1{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}/{color}{color:#001080}protocol{color}{color:#000000}.{color}{color:#af00db}go{color}{color:#000000}:{color}{color:#098658}82{color}{color:#000000}
 +{color}{color:#098658}0x272{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 {color}{color:#001080}created{color}{color:#000000} 
{color}{color:#001080}by{color}{color:#000000} 
{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}.{color}{color:#001080}newGremlinServerWSProtocol{color}{color:#000000}
 {color}{color:#001080}in{color}{color:#000000} 
{color}{color:#001080}goroutine{color}{color:#000000} 
{color}{color:#098658}272{color}
{color:#098658}10{color}{color:#000000}:{color}{color:#098658}22{color}{color:#000000}:{color}{color:#098658}44.487{color}{color:#000000}
 
/{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}pkg{color}{color:#000000}/{color}{color:#001080}mod{color}{color:#000000}/{color}{color:#001080}github{color}{color:#000000}.{color}{color:#001080}com{color}{color:#000000}/{color}{color:#001080}apache{color}{color:#000000}/{color}{color:#001080}tinkerpop{color}{color:#000000}/{color}{color:#001080}gremlin{color}{color:#000000}-{color}{color:#af00db}go{color}{color:#000000}/{color}{color:#001080}v3{color}{color:#000000}@{color}{color:#001080}v3{color}{color:#000000}.{color}{color:#098658}7.1{color}{color:#000000}/{color}{color:#001080}driver{color}{color:#000000}/{color}{color:#001080}protocol{color}{color:#000000}.{color}{color:#af00db}go{color}{color:#000000}:{color}{color:#098658}197{color}{color:#000000}
 +{color}{color:#098658}0x23a{color}
```

 

I can't reliably reproduce, it's never happened locally. It's occurred just 
after doing some work in the logs above, but it's also happened after a period 
of doing nothing.

 

First glance looks like it's a nil being returned from the `resultSets` 
synchronizedMap, something getting in and removing it, which should only happen 
when the `channelResultSet` itself is closed? Seems like a race condition to me.

I think the sensible way to handle this, if it is what I suspect (I've no proof 
yet), would be to
 * Store a reference to the ResultSet when first loading it in responseHandler
 * Make `channelResultSet` discard modifications after close OR
 * responseHandler needs to aquire the `channelMutex` somehow for the duration 
of modifications (I think I prefer this, it's more obvious to what's happening)

I did try and get the project tests to run, but it's been _years_ since I've 
had to use maven and I can't seem to find a good idiots guide to working with 
the project from a non java POV - I need to know how to build the docker images 
the tests require. If someone could help me get started I'd be more than happy 
to contribute a PR (although given the nature, a reliable test may be hard to 
write).

As it stands, I'm probably going to modify my fork and mod replace, see if a 
fix would actually work in my deployments.


> Panic in gremlin-go driver responseHandler
> ------------------------------------------
>
>                 Key: TINKERPOP-3087
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-3087
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: go
>    Affects Versions: 3.7.1
>         Environment: Ubuntu 20.04, x86_64, AWS EC2 image. Think it's 2c2g, 
> can't recall off the top of my head.
> Compiled _without_ CGO.
>            Reporter: David Bennington
>            Priority: Minor
>
> Ocasionally, I get the following panic in the gremlin-go driver:
>  
> {noformat}
> 10:22:39.895 <successfully added a vertex to janusgraph>
> 10:22:44.487 panic: runtime error: invalid memory address or nil pointer 
> dereference
> 10:22:44.487 [signal SIGSEGV: segmentation violation code=0x1 addr=0x78 
> pc=0x11fdd16]
> 10:22:44.487 
> 10:22:44.487 goroutine 275 [running]:
> 10:22:44.487 
> github.com/apache/tinkerpop/gremlin-go/v3/driver.(*gremlinServerWSProtocol).responseHandler(0xc0006be6c0,
>  0xc0001dfc60, {{0x9, 0xf6, 0x33, 0x7f, 0x19, 0x16, 0x4e, 0xc9, ...}, ...})
> 10:22:44.487 
> /go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:116
>  +0x7d6
> 10:22:44.487 
> github.com/apache/tinkerpop/gremlin-go/v3/driver.(*gremlinServerWSProtocol).readLoop(0xc0006be6c0,
>  0xc0001dfc60, 0xc0001dfca0)
> 10:22:44.487 
> /go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:82
>  +0x272
> 10:22:44.487 created by 
> github.com/apache/tinkerpop/gremlin-go/v3/driver.newGremlinServerWSProtocol 
> in goroutine 272
> 10:22:44.487 
> /go/pkg/mod/github.com/apache/tinkerpop/gremlin-go/v3@v3.7.1/driver/protocol.go:197
>  +0x23a{noformat}
> I can't reliably reproduce, it's never happened locally. It's occurred just 
> after doing some work in the logs above, but it's also happened after a 
> period of doing nothing.
>  
> First glance looks like it's a nil being returned from the `resultSets` 
> synchronizedMap, something getting in and removing it, which should only 
> happen when the `channelResultSet` itself is closed? Seems like a race 
> condition to me.
> I think the sensible way to handle this, if it is what I suspect (I've no 
> proof yet), would be to
>  * Store a reference to the ResultSet when first loading it in responseHandler
>  * Make `channelResultSet` discard modifications after close OR
>  * responseHandler needs to aquire the `channelMutex` somehow for the 
> duration of modifications (I think I prefer this, it's more obvious to what's 
> happening)
> I did try and get the project tests to run, but it's been _years_ since I've 
> had to use maven and I can't seem to find a good idiots guide to working with 
> the project from a non java POV - I need to know how to build the docker 
> images the tests require. If someone could help me get started I'd be more 
> than happy to contribute a PR (although given the nature, a reliable test may 
> be hard to write).
> As it stands, I'm probably going to modify my fork and mod replace, see if a 
> fix would actually work in my deployments.



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