Panic during shutdown of multiple aggregators

[KevinJoiner]

Relevant telegraf.conf:

[[outputs.file]]
        files = ["stdout"]
[[inputs.exec]]
        commands = ["python -c print(5)"]
        interval = "1s"
        data_format = "value"
        data_type = "integer"
[[aggregators.valuecounter]]
        drop_original = false
        period = "5s"
        fields = ["value"]
[[aggregators.valuecounter]]
        drop_original = false
        period = "5s"
        fields = ["value"]

System info:

Telegraf 1.9.1
OS: RHEL 7.6

Steps to reproduce:

1. Run Telegraf with two or more aggregator plugins.
2. Stop Telegraf with kill -SIGTERM <PID> or keyboard interrupt

Expected behavior:

Telegraf gracefully stops

Actual behavior:

"panic: send on closed channel"

[glinton]

Can you include the full stack trace from the panic, please?

[KevinJoiner]

panic: send on closed channel

goroutine 25 [running]:
github.com/influxdata/telegraf/agent.(*accumulator).addFields(0xc000167580, 0xc0001814d0, 0x4, 0xc000423740, 0xc000423d40, 0x3, 0x0, 0x0, 0x0)
        /go/src/github.com/influxdata/telegraf/agent/accumulator.go:102 +0x16f
github.com/influxdata/telegraf/agent.(*accumulator).AddFields(0xc000167580, 0xc0001814d0, 0x4, 0xc000423d40, 0xc000423740, 0x0, 0x0, 0x0)
        /go/src/github.com/influxdata/telegraf/agent/accumulator.go:45 +0x83
github.com/influxdata/telegraf/plugins/aggregators/valuecounter.(*ValueCounter).Push(0xc000166ae0, 0x25218c0, 0xc000167580)
        /go/src/github.com/influxdata/telegraf/plugins/aggregators/valuecounter/valuecounter.go:95 +0x1a8
github.com/influxdata/telegraf/internal/models.(*RunningAggregator).push(0xc000236000, 0x25218c0, 0xc000167580)
        /go/src/github.com/influxdata/telegraf/internal/models/running_aggregator.go:146 +0x6e
github.com/influxdata/telegraf/internal/models.(*RunningAggregator).Push(0xc000236000, 0x25218c0, 0xc000167580)
        /go/src/github.com/influxdata/telegraf/internal/models/running_aggregator.go:140 +0x11f
github.com/influxdata/telegraf/agent.(*Agent).push(0xc00000e288, 0x2513c20, 0xc0002e41c0, 0xc000236000, 0x25218c0, 0xc000167580)
        /go/src/github.com/influxdata/telegraf/agent/agent.go:427 +0x177
github.com/influxdata/telegraf/agent.(*Agent).runAggregators.func2(0xc00023e020, 0xc00000e288, 0x2513c20, 0xc0002e41c0, 0xbf1ef62147dfc4ab, 0x3880f03, 0x3ce6540, 0x2540be400, 0xc00007db60, 0x0, ...)
        /go/src/github.com/influxdata/telegraf/agent/agent.go:395 +0x157
created by github.com/influxdata/telegraf/agent.(*Agent).runAggregators
        /go/src/github.com/influxdata/telegraf/agent/agent.go:379 +0x239