Client.Close() blocked by write API Flush() (if (?) it can't send metrics)

[i-prudnikov]

Steps to reproduce:

1. Instantiate client and use non blocking write API
2. Experience error while sending data (in my case I got the following error):

influxdb2client E! Write error: unprocessable entity: failure writing points to database: partial write: field type conflict: input field "value" on measurement "xxxxxx" is type unsigned, already exists as type integer dropped=28

3. De init client by calling client.Close()

Expected behaviour:
client.Close() will not block by unsuccessful flushing.

Actual behavior:
client.Close() blocked by calling write API Flush():
Stack trace of blocked goroutine:

runtime.gopark(proc.go:367)
runtime.chansend(chan.go:257)
runtime.chansend1(chan.go:143)
github.com/influxdata/influxdb-client-go/v2/api.(*WriteAPIImpl).waitForFlushing(write.go:125)
github.com/influxdata/influxdb-client-go/v2/api.(*WriteAPIImpl).Flush(write.go:111)
github.com/influxdata/influxdb-client-go/v2/api.(*WriteAPIImpl).Close(write.go:199)
github.com/influxdata/influxdb-client-go/v2.(*clientImpl).Close(client.go:242)

Specifications:

• Client Version: 2.8.0
• InfluxDB Version: 2.1.1
• Platform: Client - Darwin, Server - Linux

[vlastahajek]

@i-prudnikov, I cannot reproduce this. There is no logic for waiting for unsuccessful writes. Flushing could be blocked if you have another routine which is still writing when you are closing the client.
Could you, please, enable debug logging, reproduce the issue, and past the log here?

[i-prudnikov]

Hi @vlastahajek,
I did double check and found out that the reason of blocking is channel returned by writeAPI.Errors()
So if writeAPI is asked for a channel even like this _ = writeAPI.Errors() then it leads to a deadlock if error occurred but the error channel is not pooled. So looks like a feature not a bug. Though I would vote for a non-blocking write into an error channel, otherwise seemed confusing.
Feel free to close the issue.