remove env maxMemory; default max/2 or 1GB

Author: kczimm

README.md

@@ -124,16 +124,14 @@ handle other errors, for example RESOURCE_EXHAUSTED (HTTP 429).
 
 ### Memory Configuration
 
-The `SpiceClient` uses an Arrow `RootAllocator` for managing off-heap memory. By default, it allows unlimited memory allocation. To prevent OOM issues in constrained environments, you can limit the maximum memory:
+The `SpiceClient` uses an Arrow `RootAllocator` for managing off-heap memory. By default, it limits memory to 50% of the JVM's maximum heap size or 1GB, whichever is lower. To prevent OOM issues in constrained environments, you can limit the maximum memory:
 
 ```java
 SpiceClient client = SpiceClient.builder()
     .withMaxMemory(1024 * 1024 * 1024L) // 1GB limit
     .build();
 ```
 
-You can also set the limit via the `SPICE_MAX_MEMORY` environment variable (in bytes). If both are provided, the builder method takes precedence.
-
 ### Spice.ai Runtime commands
 
 #### Accelerated dataset refresh

src/main/java/ai/spice/Config.java

@@ -93,25 +93,6 @@ public static URI getCloudHttpAddressUri() throws URISyntaxException {
         return new URI(CLOUD_HTTP_ADDRESS);
     }
 
-    /**
-     * Returns the maximum memory allocation for the Arrow RootAllocator from the
-     * SPICE_MAX_MEMORY environment variable.
-     *
-     * @return the maximum memory in bytes, or Long.MAX_VALUE if not set or invalid.
-     */
-    public static long getMaxMemory() {
-        try {
-            String maxMemoryStr = System.getenv("SPICE_MAX_MEMORY");
-            long maxMemory = Long.parseLong(maxMemoryStr);
-            if (maxMemory > 0) {
-                return maxMemory;
-            }
-        } catch (Exception e) {
-            // Any exception, fall back to default
-        }
-        return Long.MAX_VALUE;
-    }
-
     /**
      * Returns the Spice SDK user agent for this system, including the package
      * version, system OS, version and arch.

src/main/java/ai/spice/SpiceClientBuilder.java

@@ -40,6 +40,19 @@ public class SpiceClientBuilder {
     private int maxRetries = 3;
     private long maxMemory = Long.MAX_VALUE;
 
+    /**
+     * Calculates the default maximum memory for the Arrow RootAllocator.
+     * Returns 50% of the JVM's maximum heap size or 1GB, whichever is lower.
+     *
+     * @return the default maximum memory in bytes.
+     */
+    private static long calculateDefaultMaxMemory() {
+        long jvmMaxMemory = Runtime.getRuntime().maxMemory();
+        long halfMemory = jvmMaxMemory / 2;
+        long oneGB = 1024L * 1024 * 1024;
+        return Math.min(halfMemory, oneGB);
+    }
+
     /**
      * Constructs a new SpiceClientBuilder instance
      *
@@ -48,7 +61,7 @@ public class SpiceClientBuilder {
     SpiceClientBuilder() throws URISyntaxException {
         this.flightAddress = Config.getLocalFlightAddressUri();
         this.httpAddress = Config.getLocalHttpAddressUri();
-        this.maxMemory = Config.getMaxMemory();
+        this.maxMemory = calculateDefaultMaxMemory();
     }
 
     /**