http: unexpected EOF reading trailer not a temporary error?

[Jens-Uwe Mager]

I am checking net.error for the Temporary() condition, and in my very bad network I do see really a lot of errors. While doing a GET request I see that

http: unexpected EOF reading trailer

is not a temporary error, so my retry logic does not kick in. Is this a special case or just an oversight?

[Ian Lance Taylor]

EOF means that the TCP connection has closed, so this error is not temporary.

Ian

[Jens-Uwe Mager]

Looking further into this, I see this as a typical transient error in a bad network on downloading files. It may be different elsewhere, but I have to retry on that error as it appears. And I cannot change the network somewhere in the Guatemala outback.

[Jakob Borg]

I think the definition of "temporary" is the issue here. Something like an underlying EAGAN is "temporary" - retrying the same operation that failed on the same socket again can succeed. A read error from a closed TCP connection is not temporary - reading again cannot possibly unclose the connection and suddenly succeed.

However, it not being a temporary error doesn’t mean that larger scale operation can never succeed - retrying by making another request can work.

In other words, for your HTTP purposes I don’t think the (*OpError).Temporary() is a valuable indicator. You’re probably better off considering known fatal HTTP errors as non-temporary (a 404 probably indicates the request won’t succeed in 500 ms either, unless you know otherwise) and other errors as transient and subject to a retry.

//jb

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