Configurare timeout e nuovi tentativi personalizzati

Questa pagina mostra come sostituire la configurazione del timeout predefinita e configurare una policy di nuovi tentativi utilizzando le librerie client di Spanner.

Le librerie client utilizzano le impostazioni predefinite di timeout e policy di nuovi tentativi definite nei seguenti file di configurazione.

Nei file di configurazione, il timeout predefinito per le operazioni che richiedono un breve periodo di tempo, ad esempio CreateSession, è di 30 secondi. Le operazioni più lunghe, come query o letture, hanno un timeout predefinito di 3600 secondi. Ti consigliamo di utilizzare questi valori predefiniti. Tuttavia, se necessario, puoi impostare un timeout personalizzato o una policy di nuovi tentativi nella tua applicazione.

Se decidi di modificare il timeout, impostalo sul periodo di tempo effettivo per cui l'applicazione è configurata per attendere il risultato.

Non configurare una policy di nuovi tentativi più aggressiva di quella predefinita, perché troppi nuovi tentativi potrebbero sovraccaricare il backend e limitare le richieste.

Una policy di nuovi tentativi è definita in ogni snippet, con le seguenti caratteristiche:

  • La durata del tempo di attesa iniziale, o di avvio, prima di riprovare la richiesta.
  • Un ritardo massimo.
  • Un moltiplicatore da utilizzare con il tempo di attesa precedente per calcolare il tempo di attesa successivo, fino al raggiungimento del valore massimo.
  • Un insieme di codici di errore per le operazioni di nuovi tentativi.

Nell'esempio seguente, per l'operazione specificata viene impostato un timeout di 60 secondi. Se l'operazione richiede più tempo di questo timeout, non va a buon fine e viene restituito un errore DEADLINE_EXCEEDED.

Se l'operazione non va a buon fine con un codice di errore UNAVAILABLE, ad esempio se si verifica un problema di rete temporaneo, viene eseguito un nuovo tentativo. Il client attende 500 ms prima di avviare il primo tentativo. Se il primo tentativo non va a buon fine, il client attende 1,5 * 500 ms = 750 ms prima di avviare il secondo tentativo. Questo ritardo di nuovi tentativi continua ad aumentare finché l'operazione non va a buon fine o non raggiunge il ritardo massimo di nuovi tentativi di 16 secondi. L'operazione non va a buon fine e viene restituito un errore DEADLINE_EXCEEDED se il tempo totale trascorso per provare l'operazione supera il valore di timeout totale di 60 secondi.

C++

namespace spanner = ::google::cloud::spanner;
using ::google::cloud::StatusOr;
[](std::string const& project_id, std::string const& instance_id,
   std::string const& database_id) {
  // Use a truncated exponential backoff with jitter to wait between
  // retries:
  //   https://en.wikipedia.org/wiki/Exponential_backoff
  //   https://cloud.google.com/storage/docs/exponential-backoff
  auto client = spanner::Client(spanner::MakeConnection(
      spanner::Database(project_id, instance_id, database_id),
      google::cloud::Options{}
          .set<spanner::SpannerRetryPolicyOption>(
              std::make_shared<spanner::LimitedTimeRetryPolicy>(
                  /*maximum_duration=*/std::chrono::seconds(60)))
          .set<spanner::SpannerBackoffPolicyOption>(
              std::make_shared<spanner::ExponentialBackoffPolicy>(
                  /*initial_delay=*/std::chrono::milliseconds(500),
                  /*maximum_delay=*/std::chrono::seconds(16),
                  /*scaling=*/1.5))));

  std::int64_t rows_inserted;
  auto commit_result = client.Commit(
      [&client, &rows_inserted](
          spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
        auto insert = client.ExecuteDml(
            std::move(txn),
            spanner::SqlStatement(
                "INSERT INTO Singers (SingerId, FirstName, LastName)"
                "  VALUES (20, 'George', 'Washington')"));
        if (!insert) return std::move(insert).status();
        rows_inserted = insert->RowsModified();
        return spanner::Mutations{};
      });
  if (!commit_result) throw std::move(commit_result).status();
  std::cout << "Rows inserted: " << rows_inserted;
}

C#


using Google.Api.Gax;
using Google.Api.Gax.Grpc;
using Google.Cloud.Spanner.Common.V1;
using Google.Cloud.Spanner.V1;
using Grpc.Core;
using System;
using System.Threading;
using System.Threading.Tasks;
using static Google.Cloud.Spanner.V1.TransactionOptions.Types;

public class CustomTimeoutsAndRetriesAsyncSample
{
    public async Task<long> CustomTimeoutsAndRetriesAsync(string projectId, string instanceId, string databaseId)
    {
        // Create a SessionPool.
        SpannerClient client = SpannerClient.Create();
        SessionPool sessionPool = new SessionPool(client, new SessionPoolOptions());

        // Acquire a session with a read-write transaction to run a query.
        DatabaseName databaseName =
            DatabaseName.FromProjectInstanceDatabase(projectId, instanceId, databaseId);
        TransactionOptions transactionOptions = new TransactionOptions
        {
            ReadWrite = new ReadWrite()
        };
        using PooledSession session = await sessionPool.AcquireSessionAsync(
            databaseName, transactionOptions, CancellationToken.None);

        ExecuteSqlRequest request = new ExecuteSqlRequest
        {
            Sql = "INSERT Singers (SingerId, FirstName, LastName) VALUES (20, 'George', 'Washington')"
        };

        // Prepare the call settings with custom timeout and retry settings.
        CallSettings settings = CallSettings
            .FromExpiration(Expiration.FromTimeout(TimeSpan.FromSeconds(60)))
            .WithRetry(RetrySettings.FromExponentialBackoff(
                maxAttempts: 12,
                initialBackoff: TimeSpan.FromMilliseconds(500),
                maxBackoff: TimeSpan.FromSeconds(16),
                backoffMultiplier: 1.5,
                retryFilter: RetrySettings.FilterForStatusCodes(
                    new StatusCode[] { StatusCode.Unavailable })));

        ResultSet result = await session.ExecuteSqlAsync(request, settings);
        await session.CommitAsync(new CommitRequest(), null);

        return result.Stats.RowCountExact;
    }
}

Vai


import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/spanner"
	spapi "cloud.google.com/go/spanner/apiv1"
	gax "github.com/googleapis/gax-go/v2"
	"google.golang.org/grpc/codes"
)

func setCustomTimeoutAndRetry(w io.Writer, db string) error {
	// Set a custom retry setting.
	co := &spapi.CallOptions{
		ExecuteSql: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    500 * time.Millisecond,
					Max:        16000 * time.Millisecond,
					Multiplier: 1.5,
				})
			}),
		},
	}
	client, err := spanner.NewClientWithConfig(context.Background(), db, spanner.ClientConfig{CallOptions: co})
	if err != nil {
		return err
	}
	defer client.Close()

	// Set timeout to 60s.
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()

	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		stmt := spanner.Statement{
			SQL: `INSERT Singers (SingerId, FirstName, LastName)
					VALUES (20, 'George', 'Washington')`,
		}

		rowCount, err := txn.Update(ctx, stmt)
		if err != nil {
			return err
		}
		fmt.Fprintf(w, "%d record(s) inserted.\n", rowCount)
		return nil
	})
	return err
}

Java


import com.google.api.gax.retrying.RetrySettings;
import com.google.api.gax.rpc.StatusCode.Code;
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
import org.threeten.bp.Duration;

class CustomTimeoutAndRetrySettingsExample {

  static void executeSqlWithCustomTimeoutAndRetrySettings() {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "my-project";
    String instanceId = "my-instance";
    String databaseId = "my-database";

    executeSqlWithCustomTimeoutAndRetrySettings(projectId, instanceId, databaseId);
  }

  // Create a Spanner client with custom ExecuteSql timeout and retry settings.
  static void executeSqlWithCustomTimeoutAndRetrySettings(
      String projectId, String instanceId, String databaseId) {
    SpannerOptions.Builder builder = SpannerOptions.newBuilder().setProjectId(projectId);
    // Set custom timeout and retry settings for the ExecuteSql RPC.
    // This must be done in a separate chain as the setRetryableCodes and setRetrySettings methods
    // return a UnaryCallSettings.Builder instead of a SpannerOptions.Builder.
    builder
        .getSpannerStubSettingsBuilder()
        .executeSqlSettings()
        // Configure which errors should be retried.
        .setRetryableCodes(Code.UNAVAILABLE)
        .setRetrySettings(
            RetrySettings.newBuilder()
                // Configure retry delay settings.
                // The initial amount of time to wait before retrying the request.
                .setInitialRetryDelay(Duration.ofMillis(500))
                // The maximum amount of time to wait before retrying. I.e. after this value is
                // reached, the wait time will not increase further by the multiplier.
                .setMaxRetryDelay(Duration.ofSeconds(16))
                // The previous wait time is multiplied by this multiplier to come up with the next
                // wait time, until the max is reached.
                .setRetryDelayMultiplier(1.5)

                // Configure RPC and total timeout settings.
                // Timeout for the first RPC call. Subsequent retries will be based off this value.
                .setInitialRpcTimeout(Duration.ofSeconds(60))
                // The max for the per RPC timeout.
                .setMaxRpcTimeout(Duration.ofSeconds(60))
                // Controls the change of timeout for each retry.
                .setRpcTimeoutMultiplier(1.0)
                // The timeout for all calls (first call + all retries).
                .setTotalTimeout(Duration.ofSeconds(60))
                .build());
    // Create a Spanner client using the custom retry and timeout settings.
    try (Spanner spanner = builder.build().getService()) {
      DatabaseClient client =
          spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
      client
          .readWriteTransaction()
          .run(transaction -> {
            String sql =
                "INSERT INTO Singers (SingerId, FirstName, LastName)\n"
                    + "VALUES (20, 'George', 'Washington')";
            long rowCount = transaction.executeUpdate(Statement.of(sql));
            System.out.printf("%d record inserted.%n", rowCount);
            return null;
          });
    }
  }
}

Node.js

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Creates a client
const spanner = new Spanner({
  projectId: projectId,
});
const UNAVAILABLE_STATUS_CODE = 14;
const retryAndTimeoutSettings = {
  retry: {
    // The set of error codes that will be retried.
    retryCodes: [UNAVAILABLE_STATUS_CODE],
    backoffSettings: {
      // Configure retry delay settings.
      // The initial amount of time to wait before retrying the request.
      initialRetryDelayMillis: 500,
      // The maximum amount of time to wait before retrying. I.e. after this
      // value is reached, the wait time will not increase further by the
      // multiplier.
      maxRetryDelayMillis: 16000,
      // The previous wait time is multiplied by this multiplier to come up
      // with the next wait time, until the max is reached.
      retryDelayMultiplier: 1.5,

      // Configure RPC and total timeout settings.
      // Timeout for the first RPC call. Subsequent retries will be based off
      // this value.
      initialRpcTimeoutMillis: 60000,
      // Controls the change of timeout for each retry.
      rpcTimeoutMultiplier: 1.0,
      // The max for the per RPC timeout.
      maxRpcTimeoutMillis: 60000,
      // The timeout for all calls (first call + all retries).
      totalTimeoutMillis: 60000,
    },
  },
};

// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
const table = database.table('Singers');

const row = {
  SingerId: 16,
  FirstName: 'Martha',
  LastName: 'Waller',
};

await table.insert(row, retryAndTimeoutSettings);

console.log('record inserted.');

Python

from google.api_core import exceptions as core_exceptions
from google.api_core import retry

# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)

retry = retry.Retry(
    # Customize retry with an initial wait time of 500 milliseconds.
    initial=0.5,
    # Customize retry with a maximum wait time of 16 seconds.
    maximum=16,
    # Customize retry with a wait time multiplier per iteration of 1.5.
    multiplier=1.5,
    # Customize retry with a timeout on
    # how long a certain RPC may be retried in
    # case the server returns an error.
    timeout=60,
    # Configure which errors should be retried.
    predicate=retry.if_exception_type(
        core_exceptions.ServiceUnavailable,
    ),
)

# Set a custom retry and timeout setting.
with database.snapshot() as snapshot:
    results = snapshot.execute_sql(
        "SELECT SingerId, AlbumId, AlbumTitle FROM Albums",
        # Set custom retry setting for this request
        retry=retry,
        # Set custom timeout of 60 seconds for this request
        timeout=60,
    )

    for row in results:
        print("SingerId: {}, AlbumId: {}, AlbumTitle: {}".format(*row))

Ruby

# project_id  = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"

require "google/cloud/spanner"

spanner   = Google::Cloud::Spanner.new project: project_id
client    = spanner.client instance_id, database_id
row_count = 0

timeout = 60.0
retry_policy = {
  initial_delay: 0.5,
  max_delay:     16.0,
  multiplier:    1.5,
  retry_codes:   ["UNAVAILABLE"]
}
call_options = { timeout: timeout, retry_policy: retry_policy }

client.transaction do |transaction|
  row_count = transaction.execute_update(
    "INSERT INTO Singers (SingerId, FirstName, LastName) VALUES (10, 'Virginia', 'Watson')",
    call_options: call_options
  )
end

puts "#{row_count} record inserted."