remove shared writer for now

Signed-off-by: Jay DeLuca <jaydeluca4@gmail.com>

Author: jaydeluca

benchmarks/src/main/java/io/prometheus/metrics/benchmarks/HistogramTextFormatBenchmark.java

@@ -8,46 +8,17 @@
 import io.prometheus.metrics.model.snapshots.HistogramSnapshot.HistogramDataPointSnapshot;
 import io.prometheus.metrics.model.snapshots.Labels;
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
-import java.io.BufferedWriter;
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
-import java.io.OutputStreamWriter;
-import java.io.Writer;
-import java.nio.charset.StandardCharsets;
 import java.util.concurrent.TimeUnit;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.Fork;
 import org.openjdk.jmh.annotations.Measurement;
-import org.openjdk.jmh.annotations.Scope;
-import org.openjdk.jmh.annotations.State;
 import org.openjdk.jmh.annotations.Warmup;
 
 /**
  * Benchmarks for writing a classic histogram (10 label combinations × 12 buckets) to text formats.
- *
- * <p>Three variants per format:
- *
- * <ul>
- *   <li>{@code writeToByteArray} — OutputStream path, new BufferedWriter created per call (~41
- *       KB/op; IO stack allocation dominates).
- *   <li>{@code writeToNull} — OutputStream path to /dev/null, new BufferedWriter still created per
- *       call (same allocation as writeToByteArray; shows ByteArrayOutputStream write cost is
- *       negligible).
- *   <li>{@code reusingWriter} — Writer path, BufferedWriter reused across calls (~18 KB/op; saves
- *       the ~25 KB BufferedWriter char[] buffer and OutputStreamWriter per call).
- *   <li>{@code reusingWriterToNull} — Writer path, BufferedWriter reused, output to /dev/null.
- *       Lowest-allocation floor; isolates pure formatting CPU cost with zero IO stack overhead.
- * </ul>
- *
- * <p>Key allocation sources:
- *
- * <ul>
- *   <li>BufferedWriter internal char[8192] buffer: 16,384 bytes per call (eliminated by reuse).
- *   <li>OutputStreamWriter + StreamEncoder state: ~1–2 KB per call (eliminated by reuse).
- *   <li>Remaining ~18 KB/op in reuse variants: ByteArrayOutputStream byte[] growth + any per-call
- *       String allocations remaining in the format path.
- * </ul>
+ * Output goes to /dev/null to isolate pure formatting CPU cost with zero IO overhead.
  */
 @Fork(3)
 @Warmup(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
@@ -84,110 +55,17 @@ public class HistogramTextFormatBenchmark {
   private static final PrometheusTextFormatWriter PROMETHEUS_TEXT_FORMAT_WRITER =
       PrometheusTextFormatWriter.create();
 
-  @State(Scope.Benchmark)
-  public static class WriterState {
-
-    final ByteArrayOutputStream byteArrayOutputStream;
-
-    public WriterState() {
-      this.byteArrayOutputStream = new ByteArrayOutputStream();
-    }
-  }
-
-  @State(Scope.Benchmark)
-  public static class ReusableWriterState {
-
-    final ByteArrayOutputStream openMetricsByteArrayOutputStream;
-    final ByteArrayOutputStream prometheusByteArrayOutputStream;
-    final BufferedWriter openMetricsWriter;
-    final BufferedWriter prometheusWriter;
-
-    public ReusableWriterState() {
-      this.openMetricsByteArrayOutputStream = new ByteArrayOutputStream();
-      this.prometheusByteArrayOutputStream = new ByteArrayOutputStream();
-      this.openMetricsWriter =
-          new BufferedWriter(
-              new OutputStreamWriter(openMetricsByteArrayOutputStream, StandardCharsets.UTF_8));
-      this.prometheusWriter =
-          new BufferedWriter(
-              new OutputStreamWriter(prometheusByteArrayOutputStream, StandardCharsets.UTF_8));
-    }
-  }
-
-  @State(Scope.Benchmark)
-  public static class ReusableWriterToNullState {
-
-    final BufferedWriter openMetricsWriter;
-    final BufferedWriter prometheusWriter;
-
-    public ReusableWriterToNullState() {
-      OutputStream nullOutputStream = TextFormatUtilBenchmark.NullOutputStream.INSTANCE;
-      this.openMetricsWriter =
-          new BufferedWriter(new OutputStreamWriter(nullOutputStream, StandardCharsets.UTF_8));
-      this.prometheusWriter =
-          new BufferedWriter(new OutputStreamWriter(nullOutputStream, StandardCharsets.UTF_8));
-    }
-  }
-
-  @Benchmark
-  public OutputStream openMetricsWriteToByteArray(WriterState writerState) throws IOException {
-    ByteArrayOutputStream byteArrayOutputStream = writerState.byteArrayOutputStream;
-    byteArrayOutputStream.reset();
-    OPEN_METRICS_TEXT_FORMAT_WRITER.write(
-        byteArrayOutputStream, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return byteArrayOutputStream;
-  }
-
   @Benchmark
   public OutputStream openMetricsWriteToNull() throws IOException {
     OutputStream nullOutputStream = TextFormatUtilBenchmark.NullOutputStream.INSTANCE;
     OPEN_METRICS_TEXT_FORMAT_WRITER.write(nullOutputStream, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
     return nullOutputStream;
   }
 
-  @Benchmark
-  public Writer openMetricsReusingWriter(ReusableWriterState state) throws IOException {
-    state.openMetricsByteArrayOutputStream.reset();
-    OPEN_METRICS_TEXT_FORMAT_WRITER.write(
-        state.openMetricsWriter, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return state.openMetricsWriter;
-  }
-
-  @Benchmark
-  public Writer openMetricsReusingWriterToNull(ReusableWriterToNullState state) throws IOException {
-    OPEN_METRICS_TEXT_FORMAT_WRITER.write(
-        state.openMetricsWriter, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return state.openMetricsWriter;
-  }
-
-  @Benchmark
-  public OutputStream prometheusWriteToByteArray(WriterState writerState) throws IOException {
-    ByteArrayOutputStream byteArrayOutputStream = writerState.byteArrayOutputStream;
-    byteArrayOutputStream.reset();
-    PROMETHEUS_TEXT_FORMAT_WRITER.write(
-        byteArrayOutputStream, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return byteArrayOutputStream;
-  }
-
   @Benchmark
   public OutputStream prometheusWriteToNull() throws IOException {
     OutputStream nullOutputStream = TextFormatUtilBenchmark.NullOutputStream.INSTANCE;
     PROMETHEUS_TEXT_FORMAT_WRITER.write(nullOutputStream, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
     return nullOutputStream;
   }
-
-  @Benchmark
-  public Writer prometheusReusingWriter(ReusableWriterState state) throws IOException {
-    state.prometheusByteArrayOutputStream.reset();
-    PROMETHEUS_TEXT_FORMAT_WRITER.write(
-        state.prometheusWriter, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return state.prometheusWriter;
-  }
-
-  @Benchmark
-  public Writer prometheusReusingWriterToNull(ReusableWriterToNullState state) throws IOException {
-    PROMETHEUS_TEXT_FORMAT_WRITER.write(
-        state.prometheusWriter, SNAPSHOTS, EscapingScheme.ALLOW_UTF8);
-    return state.prometheusWriter;
-  }
 }

prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/OpenMetrics2TextFormatWriter.java

@@ -144,11 +144,6 @@ public OpenMetrics2Properties getOpenMetrics2Properties() {
   public void write(OutputStream out, MetricSnapshots metricSnapshots, EscapingScheme scheme)
       throws IOException {
     Writer writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
-    write(writer, metricSnapshots, scheme);
-  }
-
-  public void write(Writer writer, MetricSnapshots metricSnapshots, EscapingScheme scheme)
-      throws IOException {
     MetricSnapshots merged = TextFormatUtil.mergeDuplicates(metricSnapshots);
     for (MetricSnapshot s : merged) {
       MetricSnapshot snapshot = SnapshotEscaper.escapeMetricSnapshot(s, scheme);

prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/OpenMetricsTextFormatWriter.java

@@ -114,11 +114,6 @@ public String getContentType() {
   public void write(OutputStream out, MetricSnapshots metricSnapshots, EscapingScheme scheme)
       throws IOException {
     Writer writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
-    write(writer, metricSnapshots, scheme);
-  }
-
-  public void write(Writer writer, MetricSnapshots metricSnapshots, EscapingScheme scheme)
-      throws IOException {
     MetricSnapshots merged = TextFormatUtil.mergeDuplicates(metricSnapshots);
     for (MetricSnapshot s : merged) {
       MetricSnapshot snapshot = SnapshotEscaper.escapeMetricSnapshot(s, scheme);

prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusTextFormatWriter.java

@@ -112,15 +112,10 @@ public String getContentType() {
   @Override
   public void write(OutputStream out, MetricSnapshots metricSnapshots, EscapingScheme scheme)
       throws IOException {
-    Writer writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
-    write(writer, metricSnapshots, scheme);
-  }
-
-  public void write(Writer writer, MetricSnapshots metricSnapshots, EscapingScheme scheme)
-      throws IOException {
     // See https://prometheus.io/docs/instrumenting/exposition_formats/
     // "unknown", "gauge", "counter", "stateset", "info", "histogram", "gaugehistogram", and
     // "summary".
+    Writer writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
     MetricSnapshots merged = TextFormatUtil.mergeDuplicates(metricSnapshots);
     for (MetricSnapshot s : merged) {
       MetricSnapshot snapshot = escapeMetricSnapshot(s, scheme);