Kafka timeout exception even though the linger.ms is 0 - apache-kafka

Question

In the Spring + Kafka application, batch.size is the default value 16384, and linger.ms=0. So I think when a message is created, it will imedeately sent to the broker, because 0 linger. But while running, it still get the exception sometimes.
org.apache.kafka.common.errors.TimeoutException: Expiring 1 record(s) for cn-mcd-pos-promotion-3: 30033 ms has passed since batch creation plus linger time
Most of the time, the producer is OK. Sometimes it gets this excpetion. What werid is, that all the exceptions is related with cn-mcd-pos-promotion-3.
What may cause this timeout even though the linger.ms is 0?
What is -3 meaning in cn-mcd-pos-promotion-3?
PS: The config of producer.
bootstrap.servers = [wqdcsrv3078.cn.infra:9093, wqdcsrv3079.cn.infra:9093, wqdcsrv3080.cn.infra:9095]
buffer.memory = 33554432
client.id = mcd.client
compression.type = none
connections.max.idle.ms = 540000
enable.idempotence = false
interceptor.classes = null
key.serializer = class org.apache.kafka.common.serialization.StringSerializer
linger.ms = 0
max.block.ms = 60000
max.in.flight.requests.per.connection = 5
max.request.size = 1048576
metadata.max.age.ms = 300000
metric.reporters = []
metrics.num.samples = 2
metrics.recording.level = INFO
metrics.sample.window.ms = 30000
receive.buffer.bytes = 32768
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retries = 0
retry.backoff.ms = 100
sasl.jaas.config = [hidden]
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.mechanism = SCRAM-SHA-256
security.protocol = SASL_PLAINTEXT
send.buffer.bytes = 131072
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
ssl.endpoint.identification.algorithm = null
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLS
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
transaction.timeout.ms = 60000
transactional.id = null
value.serializer = class org.springframework.kafka.support.serializer.JsonSerializer```
Could anyone help? Thanks.