Merge 551ee3a365 into 3752143b39

.github/workflows/client-tests.yaml

@@ -1,26 +0,0 @@
-name: Python Client Tests
-
-on:
-  pull_request:
-    paths:
-      - ".github/workflows/client-tests.yaml"
-      - "clients/python/**"
-
-jobs:
-  run_tests:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v2
-      - name: Set up Python
-        uses: actions/setup-python@v1
-        with:
-          python-version: 3.9
-      - name: Install
-        run: |
-          cd clients/python && pip install .
-      - name: Run tests
-        run: |
-          pip install pytest pytest-asyncio
-          export HF_TOKEN=${{ secrets.HF_TOKEN }}
-          make python-client-tests

backends/client/src/v3/client.rs

@@ -7,6 +7,7 @@ use grpc_metadata::InjectTelemetryContext;
 use pb::generate::v3::text_generation_service_client::TextGenerationServiceClient;
 use pb::generate::v3::*;
 use std::cmp::min;
+use std::collections::HashMap;
 use std::time::Duration;
 use tonic::transport::{Channel, Uri};
 use tracing::instrument;
@@ -181,6 +182,7 @@ impl Client {
                     watermark: true,
                     grammar: String::new(),
                     grammar_type: GrammarType::None as i32,
+                    logit_bias: HashMap::new(),
                 }),
                 stopping_parameters: Some(StoppingCriteriaParameters {
                     max_new_tokens,

backends/client/src/v3/sharded_client.rs

@@ -5,6 +5,7 @@ use crate::{ClientError, Result};
 use crate::v3::{Chunk, InfoResponse, Input};
 use async_trait::async_trait;
 use futures::future::join_all;
+use std::collections::HashMap;
 use tonic::transport::Uri;
 use tracing::instrument;
 use v3::client::{DecodeTimings, PrefillTimings};
@@ -244,6 +245,7 @@ impl Health for ShardedClient {
                 watermark: false,
                 grammar: String::new(),
                 grammar_type: GrammarType::None as i32,
+                logit_bias: HashMap::new(),
             }),
             stopping_parameters: Some(StoppingCriteriaParameters {
                 max_new_tokens: 1,

backends/v2/src/queue.rs

@@ -429,6 +429,7 @@ mod tests {
                     frequency_penalty: 0.0,
                     watermark: false,
                     grammar: None,
+                    logit_bias: None,
                 },
                 stopping_parameters: ValidStoppingParameters {
                     ignore_eos_token: false,

backends/v3/src/client/grpc_client.rs

@@ -7,6 +7,7 @@ use grpc_metadata::InjectTelemetryContext;
 use pb::generate::v3::text_generation_service_client::TextGenerationServiceClient;
 use pb::generate::v3::*;
 use std::cmp::min;
+use std::collections::HashMap;
 use std::time::Duration;
 use tonic::transport::{Channel, Uri};
 use tracing::instrument;
@@ -181,6 +182,7 @@ impl Client {
                     watermark: true,
                     grammar: String::new(),
                     grammar_type: GrammarType::None as i32,
+                    logit_bias: HashMap::new(),
                 }),
                 stopping_parameters: Some(StoppingCriteriaParameters {
                     max_new_tokens,

backends/v3/src/client/sharded_client.rs

@@ -10,6 +10,7 @@ use crate::client::{
 use crate::client::{Chunk, InfoResponse, Input};
 use async_trait::async_trait;
 use futures::future::join_all;
+use std::collections::HashMap;
 use tonic::transport::Uri;
 use tracing::instrument;
 
@@ -232,6 +233,7 @@ impl Health for ShardedClient {
                 watermark: false,
                 grammar: String::new(),
                 grammar_type: GrammarType::None as i32,
+                logit_bias: HashMap::new(),
             }),
             stopping_parameters: Some(StoppingCriteriaParameters {
                 max_new_tokens: 1,

backends/v3/src/queue.rs

@@ -5,6 +5,7 @@ use crate::client::{
 };
 use nohash_hasher::{BuildNoHashHasher, IntMap};
 use std::cmp::max;
+use std::collections::HashMap;
 use std::collections::VecDeque;
 use text_generation_router::infer::InferError;
 use text_generation_router::infer::InferStreamResponse;
@@ -542,6 +543,14 @@ impl From<ValidParameters> for NextTokenChooserParameters {
             watermark: value.watermark,
             grammar,
             grammar_type: grammar_type.into(),
+            logit_bias: value
+                .logit_bias
+                .map(|bias| {
+                    bias.into_iter()
+                        .map(|(token, bias)| (token.to_string(), bias as i32))
+                        .collect::<HashMap<String, i32>>()
+                })
+                .unwrap_or_default(),
         }
     }
 }
@@ -588,6 +597,7 @@ mod tests {
                     frequency_penalty: 0.0,
                     watermark: false,
                     grammar: None,
+                    logit_bias: None,
                 },
                 stopping_parameters: ValidStoppingParameters {
                     ignore_eos_token: false,

benchmark/src/lib.rs

@@ -47,6 +47,7 @@ pub async fn run(
         watermark,
         grammar: String::new(),
         grammar_type: GrammarType::None as i32,
+        logit_bias: std::collections::HashMap::new(),
     };
 
     // Initialize terminal properties

clients/python/text_generation/types.py

@@ -1,6 +1,6 @@
 from enum import Enum
 from pydantic import BaseModel, field_validator, ConfigDict
-from typing import Optional, List, Union, Any
+from typing import Optional, List, Union, Any, Dict
 
 from text_generation.errors import ValidationError
 
@@ -137,7 +137,7 @@ class ChatRequest(BaseModel):
     # decreasing the model's likelihood to repeat the same line verbatim.
     frequency_penalty: Optional[float] = None
     # Bias values for token selection
-    logit_bias: Optional[List[float]] = None
+    logit_bias: Optional[Dict[str, int]] = None
     # Whether to return log probabilities
     logprobs: Optional[bool] = None
     # Number of most likely tokens to return at each position

docs/openapi.json

@@ -995,12 +995,12 @@
             "nullable": true
           },
           "logit_bias": {
-            "type": "array",
-            "items": {
-              "type": "number",
-              "format": "float"
+            "type": "object",
+            "description": "Modify the likelihood of specified tokens appearing in the completion. Accepts a JSON object that maps tokens\n(specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically,\nthe bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model,\nbut values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should\nresult in a ban or exclusive selection of the relevant token.",
+            "additionalProperties": {
+              "type": "integer",
+              "format": "int32"
             },
-            "description": "UNUSED\nModify the likelihood of specified tokens appearing in the completion. Accepts a JSON object that maps tokens\n(specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically,\nthe bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model,\nbut values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should\nresult in a ban or exclusive selection of the relevant token.",
             "nullable": true
           },
           "logprobs": {
@@ -1589,6 +1589,17 @@
             "default": "null",
             "nullable": true
           },
+          "logit_bias": {
+            "type": "object",
+            "description": "Modify the likelihood of specified tokens appearing in the completion.\nAccepts a hash map that maps token strings to an associated bias value.",
+            "default": "null",
+            "additionalProperties": {
+              "type": "integer",
+              "format": "int32"
+            },
+            "example": "{\"1923\": 100, \"1924\": -100}",
+            "nullable": true
+          },
           "max_new_tokens": {
             "type": "integer",
             "format": "int32",

integration-tests/models/__snapshots__/test_flash_logit_bias/test_logit_bias_baseline.json

@@ -0,0 +1,26 @@
+{
+  "choices": [
+    {
+      "finish_reason": "length",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "Hello! How can I help you today?",
+        "name": null,
+        "role": "assistant",
+        "tool_calls": null
+      },
+      "usage": null
+    }
+  ],
+  "created": 1745337495,
+  "id": "",
+  "model": "Qwen/Qwen2-VL-2B-Instruct",
+  "object": "chat.completion",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": {
+    "completion_tokens": 10,
+    "prompt_tokens": 21,
+    "total_tokens": 31
+  }
+}

integration-tests/models/__snapshots__/test_flash_logit_bias/test_logit_bias_english_to_spanish.json

@@ -0,0 +1,26 @@
+{
+  "choices": [
+    {
+      "finish_reason": "length",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "¡Hola! ¿Cómo puedo ayudarte?",
+        "name": null,
+        "role": "assistant",
+        "tool_calls": null
+      },
+      "usage": null
+    }
+  ],
+  "created": 1746486174,
+  "id": "",
+  "model": "Qwen/Qwen2-VL-2B-Instruct",
+  "object": "chat.completion",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": {
+    "completion_tokens": 10,
+    "prompt_tokens": 21,
+    "total_tokens": 31
+  }
+}

integration-tests/models/__snapshots__/test_flash_logit_bias/test_logit_bias_multiple_tokens.json

@@ -0,0 +1,26 @@
+{
+  "choices": [
+    {
+      "finish_reason": "stop",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "Chat!",
+        "name": null,
+        "role": "assistant",
+        "tool_calls": null
+      },
+      "usage": null
+    }
+  ],
+  "created": 1746486174,
+  "id": "",
+  "model": "Qwen/Qwen2-VL-2B-Instruct",
+  "object": "chat.completion",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": {
+    "completion_tokens": 3,
+    "prompt_tokens": 25,
+    "total_tokens": 28
+  }
+}

integration-tests/models/__snapshots__/test_flash_logit_bias/test_logit_bias_streaming.json

@@ -0,0 +1,20 @@
+{
+  "choices": [
+    {
+      "delta": {
+        "content": "",
+        "role": "assistant",
+        "tool_calls": null
+      },
+      "finish_reason": "length",
+      "index": 0,
+      "logprobs": null
+    }
+  ],
+  "created": 1746486174,
+  "id": "",
+  "model": "Qwen/Qwen2-VL-2B-Instruct",
+  "object": "chat.completion.chunk",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": null
+}

integration-tests/models/test_flash_logit_bias.py

@@ -0,0 +1,109 @@
+import pytest
+
+
+@pytest.fixture(scope="module")
+def logit_bias_model_handle(launcher):
+    with launcher("Qwen/Qwen2-VL-2B-Instruct") as handle:
+        yield handle
+
+
+@pytest.fixture(scope="module")
+async def logit_bias_model(logit_bias_model_handle):
+    await logit_bias_model_handle.health(300)
+    return logit_bias_model_handle.client
+
+
+@pytest.mark.private
+async def test_logit_bias_english_to_spanish(logit_bias_model, response_snapshot):
+    """Test that setting negative bias on English tokens forces output to be in Spanish"""
+    response = await logit_bias_model.chat(
+        seed=42,
+        max_tokens=10,
+        logit_bias={"9707": -100},  # Bias against 'Hello' token
+        messages=[
+            {
+                "role": "user",
+                "content": [
+                    {"type": "text", "text": "say Hello"},
+                ],
+            },
+        ],
+    )
+    assert "¡Hola!" in response.choices[0].message.content
+    assert "Hello" not in response.choices[0].message.content
+    assert response == response_snapshot
+
+
+@pytest.mark.private
+async def test_logit_bias_baseline(logit_bias_model, response_snapshot):
+    """Test baseline behavior without logit bias for comparison"""
+    response = await logit_bias_model.chat(
+        seed=42,
+        max_tokens=10,
+        messages=[
+            {
+                "role": "user",
+                "content": [
+                    {"type": "text", "text": "say Hello"},
+                ],
+            },
+        ],
+    )
+    assert "Hello" in response.choices[0].message.content
+    assert response == response_snapshot
+
+
+@pytest.mark.private
+async def test_logit_bias_multiple_tokens(logit_bias_model, response_snapshot):
+    """Test applying bias to multiple tokens simultaneously"""
+    response = await logit_bias_model.chat(
+        seed=42,
+        max_tokens=15,
+        logit_bias={
+            "9707": -100,  # Bias against 'Hello' token
+            "2880": -100,  # Bias against 'hi' token
+        },
+        messages=[
+            {
+                "role": "user",
+                "content": [
+                    {"type": "text", "text": "Give me a one-word greeting"},
+                ],
+            },
+        ],
+    )
+    assert "Hello" not in response.choices[0].message.content.lower()
+    assert "hi" not in response.choices[0].message.content.lower()
+    assert response == response_snapshot
+
+
+@pytest.mark.private
+async def test_logit_bias_streaming(logit_bias_model, response_snapshot):
+    """Test logit bias works correctly with streaming enabled"""
+    responses = await logit_bias_model.chat(
+        seed=42,
+        max_tokens=10,
+        logit_bias={"9707": -100},  # Bias against 'Hello' token
+        messages=[
+            {
+                "role": "user",
+                "content": [
+                    {"type": "text", "text": "say Hello"},
+                ],
+            },
+        ],
+        stream=True,
+    )
+
+    count = 0
+    generated = ""
+    last_response = None
+
+    async for response in responses:
+        count += 1
+        generated += response.choices[0].delta.content
+        last_response = response
+
+    assert "¡Hola!" in generated
+    assert "Hello" not in generated
+    assert last_response == response_snapshot

proto/v3/generate.proto

@@ -104,6 +104,8 @@ message NextTokenChooserParameters {
   string grammar = 10;
   /// grammar type
   GrammarType grammar_type = 11;
+  /// logit bias dictionary mapping token string to bias value
+  map<string, int32> logit_bias = 12;
 }
 
 message StoppingCriteriaParameters {

router/src/lib.rs

@@ -18,6 +18,7 @@ use crate::infer::{Infer, InferError};
 use pyo3::prelude::*;
 use pyo3::types::IntoPyDict;
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 use tokenizers::Encoding;
 use tracing::warn;
 use utoipa::ToSchema;
@@ -431,6 +432,16 @@ pub(crate) struct GenerateParameters {
     #[serde(default)]
     #[schema(nullable = true, default = "null", example = "null")]
     pub adapter_id: Option<String>,
+
+    /// Modify the likelihood of specified tokens appearing in the completion.
+    /// Accepts a hash map that maps token strings to an associated bias value.
+    #[serde(default)]
+    #[schema(
+        nullable = true,
+        default = "null",
+        example = "{\"1923\": 100, \"1924\": -100}"
+    )]
+    pub logit_bias: Option<HashMap<String, i32>>,
 }
 
 fn default_parameters() -> GenerateParameters {
@@ -454,9 +465,9 @@ fn default_parameters() -> GenerateParameters {
         top_n_tokens: None,
         grammar: None,
         adapter_id: None,
+        logit_bias: None,
     }
 }
-
 #[derive(Clone, Deserialize, Serialize, ToSchema, Debug)]
 #[serde(try_from = "PromptDeserializer")]
 pub struct Prompt(pub Vec<String>);
@@ -841,14 +852,13 @@ pub(crate) struct ChatRequest {
     #[schema(example = "1.0")]
     pub frequency_penalty: Option<f32>,
 
-    /// UNUSED
     /// Modify the likelihood of specified tokens appearing in the completion. Accepts a JSON object that maps tokens
     /// (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically,
     /// the bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model,
     /// but values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should
     /// result in a ban or exclusive selection of the relevant token.
     #[serde(default)]
-    pub logit_bias: Option<Vec<f32>>,
+    pub logit_bias: Option<HashMap<String, i32>>,
 
     /// Whether to return log probabilities of the output tokens or not. If true, returns the log probabilities of each
     /// output token returned in the content of message.
@@ -954,6 +964,7 @@ impl ChatRequest {
             frequency_penalty,
             top_p,
             top_logprobs,
+            logit_bias,
             ..
         } = self;
 
@@ -1029,6 +1040,7 @@ impl ChatRequest {
                     top_n_tokens: top_logprobs,
                     grammar,
                     adapter_id: model.filter(|m| *m != "tgi"),
+                    logit_bias,
                 },
             },
             using_tools,

router/src/server.rs

@@ -798,6 +798,7 @@ pub(crate) async fn completions(
                 top_n_tokens: None,
                 grammar: None,
                 adapter_id: model.as_ref().filter(|m| *m != "tgi").map(String::from),
+                logit_bias: None,
             },
         })
         .collect();

router/src/validation.rs

@@ -34,6 +34,7 @@ pub struct Validation {
     max_input_length: usize,
     max_total_tokens: usize,
     disable_grammar_support: bool,
+    vocab_size: u32,
     /// Channel to communicate with the background tokenization task
     sender: mpsc::UnboundedSender<TokenizerRequest>,
 }
@@ -88,6 +89,19 @@ impl Validation {
             validation_sender
         };
 
+        let vocab_size = match &tokenizer {
+            Tokenizer::Python { tokenizer_name, .. } => {
+                warn!(
+                    "Tokenizer {} is not supported for validation",
+                    tokenizer_name
+                );
+                0
+            }
+            Tokenizer::Rust(tokenizer) => tokenizer.get_vocab_size(false),
+        }
+        .try_into()
+        .unwrap_or(0);
+
         Self {
             max_best_of,
             sender,
@@ -96,6 +110,7 @@ impl Validation {
             max_input_length,
             max_total_tokens,
             disable_grammar_support,
+            vocab_size,
         }
     }
 
@@ -409,6 +424,37 @@ impl Validation {
             None => None,
         };
 
+        // Validate logit bias and convert to a vector of (token_id, bias_value)
+        let logit_bias = request
+            .parameters
+            .logit_bias
+            .as_ref()
+            .filter(|bias_map| !bias_map.is_empty())
+            .map(|bias_map| {
+                bias_map
+                    .iter()
+                    .map(|(token_str, &bias_value)| {
+                        let token_id: u32 = token_str.parse().map_err(|_| {
+                            ValidationError::LogitBiasInvalid(format!(
+                                "Token ID {token_str} is not a valid number."
+                            ))
+                        })?;
+
+                        if token_id >= self.vocab_size {
+                            return Err(ValidationError::LogitBiasInvalid(format!(
+                                "Token ID {token_id} is out of range (0..{}).",
+                                self.vocab_size - 1
+                            )));
+                        }
+
+                        Ok((token_id, bias_value as f32))
+                    })
+                    .collect::<Result<Vec<_>, _>>()
+            })
+            // convert Option<Result<T, E>> to Result<Option<T>, E> to throw
+            // if any of the token IDs are invalid
+            .transpose()?;
+
         let parameters = ValidParameters {
             temperature,
             repetition_penalty,
@@ -420,6 +466,7 @@ impl Validation {
             seed,
             watermark,
             grammar,
+            logit_bias,
         };
         let stopping_parameters = ValidStoppingParameters {
             max_new_tokens,
@@ -902,6 +949,8 @@ pub struct ValidParameters {
     pub watermark: bool,
     /// / grammar (applied if not empty)
     pub grammar: Option<ValidGrammar>,
+    /// / logit bias
+    pub logit_bias: Option<Vec<(u32, f32)>>,
 }
 
 #[derive(Debug, Clone)]
@@ -997,6 +1046,8 @@ pub enum ValidationError {
     FailedFetchImage(#[from] reqwest::Error),
     #[error("{0} modality is not supported")]
     UnsupportedModality(&'static str),
+    #[error("logit_bias is not valid: {0}")]
+    LogitBiasInvalid(String),
 }
 
 #[cfg(test)]

server/text_generation_server/models/vlm_causal_lm.py

@@ -725,6 +725,15 @@ class VlmCausalLM(FlashCausalLM):
             **kwargs,
         )
 
+        if self.config.vocab_size != self.tokenizer.vocab_size:
+            logger.warning(
+                f"Tokenizer vocab size {self.tokenizer.vocab_size} does not match model vocab size {self.config.vocab_size}. Updating tokenizer vocab size."
+            )
+            # TODO: HUGE HACK! This is a workaround to update the vocab size
+            # in the tokenizer. When the tokenizer is updated within the model
+            # the vocab size is not updated in the tokenizer.
+            self.tokenizer._vocab_size = self.config.vocab_size
+
     @property
     def batch_type(self) -> Type[VlmCausalLMBatch]:
         return self.batch_class

server/text_generation_server/utils/logits_process.py

@@ -623,3 +623,85 @@ class HeterogeneousGrammarLogitProcessor(LogitsProcessor):
             new_fsms.append(self.fsms[i])
         self.fsms = new_fsms
         return self
+
+
+class LogitBiasProcessor(LogitsProcessor):
+    """
+    `LogitBiasProcessor` creates a bias tensor from a dictionary of token IDs and their
+    corresponding bias values. Bias are applied to the logits during each forward pass.
+
+    Supports token IDs provided as strings (e.g., {"9707": -100}).
+    """
+
+    def __init__(
+        self,
+        logit_biases: dict,
+        tokenizer: PreTrainedTokenizerBase,
+        device: torch.device,
+    ):
+        assert logit_biases, "LogitBiasProcessor requires non-empty logit_biases"
+
+        # use _vocab_size or fallback to tokenizer.vocab_size if not available
+        self.vocab_size = getattr(tokenizer, "_vocab_size", tokenizer.vocab_size)
+
+        # Convert keys to integers and values to a list
+        token_ids = torch.tensor(
+            [int(k) for k in logit_biases.keys()], dtype=torch.long
+        )
+        bias_values = torch.tensor(list(logit_biases.values()), dtype=torch.float)
+
+        # Create a tensor and directly copy bias values at the corresponding indices
+        self.bias_tensor = torch.zeros(self.vocab_size, dtype=torch.float)
+        self.bias_tensor.index_put_((token_ids,), bias_values, accumulate=True)
+
+    def __call__(self, input_ids: torch.Tensor, scores: torch.Tensor) -> torch.Tensor:
+        scores.add_(self.bias_tensor.to(device=scores.device, dtype=scores.dtype))
+        return scores
+
+
+class HeterogeneousLogitBiasProcessor(LogitsProcessor):
+    """
+    Process logits with different logit biases for each sequence in the batch.
+    """
+
+    def __init__(
+        self,
+        logit_biases: List[Optional[dict]],
+        tokenizer: PreTrainedTokenizerBase,
+        device: torch.device,
+    ):
+        assert logit_biases, "LogitBiasProcessor requires non-empty logit_biases"
+
+        self.tokenizer = tokenizer
+        self.logit_biases = logit_biases
+
+        # use _vocab_size or fallback to tokenizer.vocab_size if not available
+        self.vocab_size = getattr(tokenizer, "_vocab_size", tokenizer.vocab_size)
+
+        # Create batch_size x vocab_size bias matrix
+        self.bias_matrix = torch.zeros(
+            (len(logit_biases), self.vocab_size), dtype=torch.float, device=device
+        )
+
+        # for each logit bias dictionary, convert keys to integers and values to a list
+        for i, logit_bias in enumerate(logit_biases):
+            token_ids = torch.tensor(
+                [int(k) for k in logit_bias.keys()], dtype=torch.long
+            ).to(device=device)
+            bias_values = torch.tensor(list(logit_bias.values()), dtype=torch.float).to(
+                device=device
+            )
+            # Create a tensor and directly copy bias values at the corresponding indices
+            self.bias_matrix[i].index_put_((token_ids,), bias_values, accumulate=True)
+
+    def __call__(self, input_ids: torch.Tensor, scores: torch.Tensor) -> torch.Tensor:
+        scores.add_(self.bias_matrix.to(device=scores.device, dtype=scores.dtype))
+        return scores
+
+    def filter(self, indices):
+        new_logit_biases = [self.logit_biases[i] for i in indices]
+        if not any(bias and len(bias) > 0 for bias in new_logit_biases):
+            return None
+        return HeterogeneousLogitBiasProcessor(
+            new_logit_biases, self.tokenizer, self.device
+        )

server/text_generation_server/utils/tokens.py

@@ -7,6 +7,7 @@ from text_generation_server.pb.generate_pb2 import FinishReason, GrammarType
 from text_generation_server.utils.logits_process import (
     FrequencyPenaltyLogitsProcessor,
     GrammarLogitProcessor,
+    LogitBiasProcessor,
     HeterogeneousProcessorWrapper,
     HeterogeneousRepetitionPenaltyLogitsProcessor,
     HeterogeneousFrequencyPenaltyLogitsProcessor,
@@ -15,6 +16,7 @@ from text_generation_server.utils.logits_process import (
     HeterogeneousTopPLogitsWarper,
     HeterogeneousTypicalLogitsWarper,
     HeterogeneousGrammarLogitProcessor,
+    HeterogeneousLogitBiasProcessor,
     static_warper,
 )
 from text_generation_server.utils.watermark import WatermarkLogitsProcessor
@@ -38,6 +40,7 @@ class NextTokenChooser:
         grammar: str = "",
         grammar_type: GrammarType = GrammarType.GRAMMAR_TYPE_NONE,
         fsm_grammar_state: int = 0,
+        logit_bias: Optional[dict] = None,
     ):
         self.watermark_processor = (
             WatermarkLogitsProcessor(device=device) if watermark else None
@@ -57,6 +60,11 @@ class NextTokenChooser:
             if grammar != ""
             else None
         )
+        self.logit_bias_processor = (
+            LogitBiasProcessor(logit_bias, tokenizer, device)
+            if logit_bias is not None and len(logit_bias) > 0
+            else None
+        )
         self.tokenizer = tokenizer
 
         has_warpers = (
@@ -87,6 +95,8 @@ class NextTokenChooser:
             scores = self.frequency_processor(input_ids, scores)
         if self.grammar_processor is not None:
             scores = self.grammar_processor(scores, self.fsm_grammar_state)
+        if self.logit_bias_processor is not None:
+            scores = self.logit_bias_processor(input_ids, scores)
 
         if self.static_warper is None:
             next_logprob = torch.log_softmax(scores, -1)
@@ -125,6 +135,7 @@ class NextTokenChooser:
             tokenizer=tokenizer,
             grammar=pb.grammar,
             grammar_type=pb.grammar_type,
+            logit_bias=pb.logit_bias,
         )
 
 
@@ -248,6 +259,7 @@ class HeterogeneousNextTokenChooser:
         grammars: List[str],
         grammar_types: List[int],
         fsm_grammar_states=List[int],
+        logit_biases: List[Optional[dict]] = None,
     ):
         warpers = []
 
@@ -287,6 +299,12 @@ class HeterogeneousNextTokenChooser:
             else None
         )
 
+        self.logit_bias_processor = (
+            HeterogeneousLogitBiasProcessor(logit_biases, tokenizer, device)
+            if any(logit_bias for logit_bias in logit_biases)
+            else None
+        )
+
         if any(x != 1.0 for x in temperature):
             do_sample = [
                 sample or x != 1.0 for x, sample in zip(temperature, do_sample)
@@ -322,6 +340,7 @@ class HeterogeneousNextTokenChooser:
         self.fsm_grammar_states = fsm_grammar_states
         self.grammars = grammars
         self.grammar_types = grammar_types
+        self.logit_biases = logit_biases
 
     def __call__(
         self,
@@ -353,6 +372,8 @@ class HeterogeneousNextTokenChooser:
                 _scores = self.frequency_processor(input_ids, _scores)
             if self.grammar_processor is not None:
                 _scores = self.grammar_processor(_scores, self.fsm_grammar_states)
+            if self.logit_bias_processor is not None:
+                _scores = self.logit_bias_processor(input_ids, _scores)
             for warper in self.warpers:
                 _scores = warper(input_ids, _scores)
             _next_ids = self.choice(_scores)
@@ -444,6 +465,9 @@ class HeterogeneousNextTokenChooser:
         if self.grammar_processor is not None:
             self.grammar_processor = self.grammar_processor.filter(indices)
 
+        if self.logit_bias_processor is not None:
+            self.logit_bias_processor = self.logit_bias_processor.filter(indices)
+
         filtered_warpers = []
         for warper in self.warpers:
             filtered_warper = warper.filter(indices)
@@ -453,6 +477,7 @@ class HeterogeneousNextTokenChooser:
 
         self.seeds = [self.seeds[i] for i in indices]
         self.do_sample = [self.do_sample[i] for i in indices]
+        self.logit_biases = [self.logit_biases[i] for i in indices]
 
         new_grammars = []
         new_fsm_grammar_states = []
@@ -500,6 +525,7 @@ class HeterogeneousNextTokenChooser:
             fsm_grammar_states=(
                 fsm_grammar_states if fsm_grammar_states else [0] * len(pb)
             ),
+            logit_biases=[pb_.logit_bias for pb_ in pb],
         )