Problem

When we run the console program or program using presto-jdbc in JDK 11 environment, it is too slow to complete the execution. In JDK 11 environment, the program tries to construct the connection with HTTP 2 instead of HTTP 1.1.

While the coordinator does not support HTTP 2 yet, it can be a problem when we access to the coordinator through proxy or load balancer such as ALB supporting HTTP 2.

This query took several minutes to complete. api-presto.treasuredata.com is an endpoint to the public ALB supporting presto protocol.

$ ./presto-cli-317-SNAPSHOT-executable.jar \
    --server https://api-presto.treasuredata.com \
    --catalog td-presto \
    --user XXXXXXXXXXXXXXXXX \
    --execute "select 1234"

This seems to be caused by a non-daemon thread running in OkHttpClient with HTTP 2.0. (ref: https://github.com/square/okhttp/issues/4029).

Workaround

As a workaround, there are two ways to disable HTTP 2 on the client-side.

1. Use JDK 8 not to use HTTP 2
2. Specify HTTP 1.1 explicitly in the OkHttpClient as follows.

OkHttpClient.Builder builder = new OkHttpClient.Builder();
builder.protocols(Arrays.asList(Protocol.HTTP_1_1));

Both ways work for me.

Discussion

Currently, it is not a huge problem in the usual cases because Presto does not support HTTP 2 yet. But it can prevent Presto from supporting HTTP 2 migration. The issue in OkHttp says that we should close the connection pool properly by okHttpClient.connectionPool().evictAll() but it’s not a solution in the long-running program like presto-cli/presto-jdbc.

How can we support the HTTP 2 environment from presto-cli and presto-jdbc?