Performing any long running task or CPU intensive work on transport_worker threads is problematic. This is typically very bad for cluster stability.

This issue has been filed to examine the usage of transport_worked threads by ESQL, with the intention of "offloading" as much as possible, including deserialising large(ish) amounts of data.
x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/operator/exchange/ExchangeServiceTests.java
}
                    }
                }
                @Override
                public void finish() {
                    finished = true;
                }
                @Override
                public boolean isFinished() {
                    return finished;
                }
                @Override
                public void close() {
                }
            };
        }
    }
    void runConcurrentTest(
        int maxInputSeqNo,
        int maxOutputSeqNo,
        Supplier<ExchangeSource> exchangeSource,
        Supplier<ExchangeSink> exchangeSink
    ) {
        final SeqNoCollector seqNoCollector = new SeqNoCollector(maxOutputSeqNo);
        final SeqNoGenerator seqNoGenerator = new SeqNoGenerator(maxInputSeqNo);
        int numSinks = randomIntBetween(1, 8);
        int numSources = randomIntBetween(1, 8);
        List<Driver> drivers = new ArrayList<>(numSinks + numSources);
        for (int i = 0; i < numSinks; i++) {
            String description = "sink-" + i;