Possible concurrency issues, using VST connection

[ewoutp]

Reproduce using this code:

package main

import (
	"context"
	"crypto/tls"
	"fmt"
	"log"
	"sync"

	"github.com/arangodb/go-driver"
	"github.com/arangodb/go-driver/vst"
	"github.com/arangodb/go-driver/vst/protocol"
)

func createConnection() driver.Connection {
	endpoint := "vst://127.0.0.1:8529"
	config := vst.ConnectionConfig{
		Endpoints: []string{endpoint},
		Transport: protocol.TransportConfig{
			IdleConnTimeout: 0,
			Version:         protocol.Version1_1,
		},
	}

	conn, err := vst.NewConnection(config)

	if err != nil {
		panic(err)
	}

	return conn
}

func createClient() driver.Client {
	conn := createConnection()
	c, err := driver.NewClient(driver.ClientConfig{
		Connection: conn,
	})

	if err != nil {
		panic(err)
	}

	v, err := c.Version(nil)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Version: %v\n", v)

	return c
}

func listAll(c driver.Client, page int) {
	ctx := context.Background()

	db, err := c.Database(ctx, "_system")
	if err != nil {
		panic(err)
	}

	limit := 100
	aql := fmt.Sprintf("FOR v IN Foo LIMIT %d, %d RETURN v", page, limit)
	ctx = driver.WithQueryBatchSize(ctx, 100)
	listAllCursor, err := db.Query(ctx, aql, nil)
	if err != nil {
		panic(err)
	}
	defer listAllCursor.Close()

	for listAllCursor.HasMore() {
		var ent map[string]interface{}
		if _, err := listAllCursor.ReadDocument(ctx, &ent); err != nil {
			panic(err)
		}
	}
}

func main() {
	c := createClient()

	wg := sync.WaitGroup{}
	for i := 0; i < 1000; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()

			for x := 0; x < 5; x++ {
				log.Printf("i=%d, x=%d\n", i, x)
				listAll(c, i)
			}
		}(i)
	}
	wg.Wait()
}

To run, initialise a Foo collection in _system database with this query:

FOR i IN 0..100000 
INSERT { x:i, foo1:"hello",foo2:"bar", foo3:"void", foo4:true} INTO Foo

It has been seen to fail with these errors:

Nil-reference:

context.(*timerCtx).Value(0xc420625da0, 0x699680, 0x73ae90, 0xc4293a9740, 0x2)

        <autogenerated>:1 +0x32

github.com/arangodb/go-driver/vst.(*vstConnection).do(0xc420114000, 0x85fcc0, 0xc420625da0, 0x861480, 0xc420a74870, 0x85bb40, 0xc42008c370, 0x893c20, 0x85fcc0, 0xc420625da0, ...)

        /src/github.com/arangodb/go-driver/vst/connection.go:170 +0x48c

github.com/arangodb/go-driver/vst.(*vstConnection).Do(0xc420114000, 0x85fcc0, 0xc420625da0, 0x861480, 0xc420a74870, 0xc4236424f0, 0x0, 0xc420472300, 0x718228)

        /src/github.com/arangodb/go-driver/vst/connection.go:136 +0x75

github.com/arangodb/go-driver/cluster.(*clusterConnection).Do(0xc420110000, 0x85fd00, 0xc4293a96b0, 0x861480, 0xc420a74870, 0xc420a74870, 0x0, 0x0, 0x0)

        /src/github.com/arangodb/go-driver/cluster/cluster.go:142 +0x249

github.com/arangodb/go-driver.(*database).Query(0xc422b8ec20, 0x85fd00, 0xc4293a96b0, 0xc42c206510, 0x25, 0x0, 0x25, 0x0, 0x0, 0xb)

        /src/github.com/arangodb/go-driver/database_impl.go:121 +0x295

Send on closed channel

github.com/arangodb/go-driver/vst/protocol.(*Connection).processChunk(0xc4200fe070, 0x6, 0x437, 0x20470, 0xc4277b8000, 0x77f0, 0x77f0)

        /src/github.com/arangodb/go-driver/vst/protocol/connection.go:256 +0x1a6

created by github.com/arangodb/go-driver/vst/protocol.(*Connection).readChunkLoop

        /src/github.com/arangodb/go-driver/vst/protocol/connection.go:229 +0x29d

Errors we're caught on linux with ArangoDB 3.2.9